GENEVA/BRUSSELS (Reuters) – The United Nations and human rights groups warned on Tuesday that a tentative European Union deal to send back all irregular migrants to Turkey in exchange for political and financial rewards could be illegal.

“I am deeply concerned about any arrangement that would involve the blanket return of anyone from one country to another without spelling out the refugee protection safeguards under international law,” U.N. High Commissioner for Refugees Filippo Grandi told the European Parliament in Strasbourg.

He was speaking hours after the 28 EU leaders sketched an accord with Turkish Prime Minister Ahmet Davutoglu in Brussels that would grant Ankara more money to keep refugees in Turkey, faster visa-free travel for Turks and a speeding up of Ankara’s long-stalled membership talks.

Rights group Amnesty International called the proposed mass return of migrants a “death blow to the right to seek asylum”. Relief charity Doctors without Borders said it was cynical and inhumane.

But the executive European Commission insisted the deal to put an end to a mass influx of more than a million people fleeing war and poverty in the Middle East and beyond, due to be finalised next week, was fully legal.

German Chancellor Angela Merkel, who pushed for the accord to assuage anxious voters before regional elections on Sunday, said things were finally moving in the right direction after nearly a million Syrians, Iraqis, Afghans and others flooded into Germany alone last year. She denied accusations that Turkey was using refugees to blackmail Europe.

The 28 EU leaders were taken by surprise by the bold, last minute Turkish initiative, which went beyond previous plans for more limited cooperation. Unable to sign up to firm commitments immediately, they agreed to wrap up a deal at their next summit on March 17-18 but several points remain sensitive.

Migrants marooned in squalor on Greece’s frontier with Macedonia by the closure of borders further north vowed to keep trying to cross Europe to wealthy Germany, while Syrian refugees in Turkey said they too would not be deterred by the lockdown.

“We will stay here even if we all die,” said Kadriya Jasem, a 25-year-old from Aleppo in Syria, one of 13,000 people living in a makeshift camp in Idomeni on the Greek side of the border with Macedonia.

ONE-FOR-ONE

Under the tentative deal, the EU would admit one refugee directly from Turkey for each Syrian it took back from the Greek Aegean islands, and those who attempted the perilous sea route would be returned and go to the back of the queue.

The aim is to persuade Syrians and others that they have better prospects if they stay in Turkey, with increased EU funding for housing, schools and subsistence.

EU officials questioned how the one-for-one scheme would work in practice, with several EU countries objecting to any quota system for resettling refugees.

It might also be overwhelmed if the volume of migrants crossing the Aegean remains high despite increased NATO-backed sea patrols by Greece and Turkey.

Brussels sought to dismiss concerns over the legality of the proposed re-admission arrangements.

“You can be sure that the agreement that will come at the end of it will comply with both European and international law,” Commission spokesman Alexander Winterstein told a news briefing.

Commission chief Jean-Claude Juncker cited EU asylum procedure rules to argue that member states were entitled to refuse to consider a claim from a person who arrives from a safe third country.

Some Commission officials have private misgivings both about Turkey’s “safe” status, given its human rights record, and the compatibility of mass returns with asylum seekers’ right to an individual assessment of their claim, an EU source said.

It was unclear whether an eventual deal could be challenged in European or international courts. Any case might take years to reach a ruling, with EU doors closed in the meantime.

Migration experts said refugees would likely try other routes if Turkey’s closure worked. Estonia, Latvia and Lithuania have begun tightening identity controls and erecting fences on their eastern borders, fearing the Baltic region will become a new entry point for migrants.

“MISERABLE”

EU Migration Commissioner Dimitris Avramopoulos, speaking in the European Parliament, welcomed the preliminary deal and said: “We need now to ensure a quick implementation of the voluntary humanitarian scheme from Turkey and to implement projects that will further improve the situation of the Syrians in Turkey.”

But many lawmakers criticized the strategy to regain control of the influx, saying the EU must ensure people needing international protection are able to claim asylum.

“In the name of ‘realpolitik’, member states seemed ready to trample on their principles to conclude a shameful bargain with Turkey,” the French Socialist group said.

Critics denounced a cascade of border closures down the main Western Balkan migration route that has left 33,000 people stranded in Greece, causing a humanitarian catastrophe.

Avramopolus responded on Twitter: “It is our responsibility to create more legal pathways for people in need of protection to come to Europe legally and safely.

“Let me assure you that @EU_Commission does not forget and does not forsake its humanitarian duties.”

While Poland and others fretted about where the EU would find the money to double the existing 3 billion euros earmarked for Syrian refugees in Turkey, Cyprus dug in its heels on advancing Turkey’s EU accession process.

Nicosia has blocked the opening of five so-called negotiation chapters – vetting Turkish compliance with EU rules – to demand recognition by Ankara and trade access. It says it will not lift objections until Turkey opens its ports and airports to Cypriot-registered traffic.

Turkey has no diplomatic ties with Cyprus, an ethnically divided island which joined the EU split in 2004 and which is represented by the Greek Cypriot government. Ankara maintains ties with a breakaway Turkish Cypriot state in northern Cyprus.

The two Cypriot communities are negotiating a peace deal to overcome 42 years of division, but until there is movement, Nicosia looks set to keep blocking Ankara’s EU progress.

(Additional reporting by Alastair Macdonald in Brussels, Lefteris Papadimas in Idomeni, Greece, and Michele Kambas in Nicosia; Writing by Paul Taylor; Editing by Giles Elgood)

IDOMENI, Greece (Reuters) – In muddy fields straddling the border with Macedonia, a transit camp hosting up to 12,000 homeless migrants in filthy conditions is the most dramatic sign of a new crisis tearing at Greece’s frayed ties with Europe and threatening its stability.

For the last year, Greece has largely waved through nearly a million migrants who crossed the Aegean Sea from Turkey on their way to wealthier northern Europe.

Now, on top of a searing economic crisis that took it close to ejection from the euro zone a year ago, the European Union’s most enfeebled state is suddenly being turned into what Prime Minister Alexis Tsipras calls a “warehouse of souls”.

At least 30,000 people fleeing conflict or poverty in the Middle East and beyond are bottled up in Greece after Western Balkan states effectively closed their borders. Up to 3,000 more are crossing the Aegean every day despite rough winter seas.

“This is an explosive mix which could blow up at any time. You cannot, however, know when,” said Costas Panagopoulos, head of ALCO opinion pollsters.

Men, women and children from Afghanistan, Syria and Iraq are packed like sardines in a disused former airport terminal in Athens, crammed into an indoor stadium or sleeping rough in a central square, where two tried to hang themselves last week.

The influx is severely straining the resources of a country barely able to look after its own people after a six-year recession – the worst since World War Two – that has shrunk the economy by a quarter and driven unemployment above 25 percent.

After years of austerity imposed by international lenders, who are now demanding deeper cuts in old-age pensions, ordinary Greeks say they feel abandoned by the European Union.

A staggering 92 percent of respondents in a Public Issue poll published by To Vima newspaper last Sunday said they felt the EU had left Greece to fend for itself.

The poll was taken before the European Commission announced 300 million euros in emergency aid this year to support relief organizations providing food, shelter and care for the migrants. But such promises do little to soften public anger.

“I want to spit at them,” said 40-year-old Maria Constantinidou, who is unemployed. “Those European leaders .. should each take 10 migrants home, feed them, look after them and then see how difficult things are.”

While the EU and Turkey will struggle to find a consensus at an emergency summit on Monday on how to stem the influx of migrants, Greece looks set to become Europe’s waiting room for months to come.

At Idomeni, a small border town in northern Greece, men from Syria held screaming babies close to a razor wire fence on Thursday, imploring Macedonian police they be allowed to cross.

Greece says it is a victim of geography; some EU partners say Greek fecklessness forced them to reimpose border controls, putting the future of a border-free Europe at stake.

“Its like watching a slow moving train wreck,” said Theodore Couloumbis, a veteran professor of international relations who is an expert on the Balkans and Greek foreign policy.

Yanis Varoufakis, a former finance minister who took Greece to the brink of a euro zone exit last year by battling creditors over bailout terms, says the crisis was symptomatic of a moral, political and economic trauma in the EU.

“Greece has been, as it always is, the weakest link in the organism and shows the biggest symptoms of disease,” he told Reuters.

CRISIS IN A CRISIS

The initial response from the public has been an outpouring of generosity towards stranded migrants, although a neo-fascist party, Golden Dawn, which advocates forcing immigrants out of Greece, has captured 7 percent of the vote in recent elections.

The migrant crisis threatens a nascent economic turnaround forecast in Greece from the second half of 2016, after six years of deep recession. Business leaders and the central bank have warned that the uncertainty could be a drag on the economy.

The main uncertainty factor is stalled negotiations between Athens and its creditors – the euro zone, the European Central Bank and the International Monetary Fund.

A first review of economic reforms under the bailout plan agreed last August, which Greece wants concluded fast to move on to debt relief talks, has been held up by disagreement among the lenders over how much more Athens needs to save in public spending, notably on pensions.

Finance Minister Euclid Tsakalotos insisted on Thursday that cuts in basic pensions were a “red line” for the government.

Publicly at least, nobody is making linkages between the refugee crisis and the bailout review or discussing trade-offs between the two, which are being handled separately.

“It is certainly not my intention to say, ‘look, I have a refugee crisis and that gives me leeway to operate beyond the framework of the (bailout) agreement’,” Tsipras said in a television interview this week. “The agreement will be kept.”

One of the most hawkish creditors, Dutch Prime Minister Mark Rutte told Reuters that while the EU should give Greece humanitarian aid, the bailout program must be kept separate.

Greece is funded till July when it faces bond repayments to the ECB, so there is no immediate financial pressure.

But a worsening migrant flow could further complicate Tsipras’ attempts to sell painful bailout reforms to a public which already feels maltreated by its EU partners.

And some policymakers in Brussels, Paris and even Berlin acknowledge that having averted a Greek exit from the euro last year, this would be the worst time for another Greek financial meltdown or political upheaval.

Greeks don’t need much prompting to take to the streets. Mass protests are a regular feature in a volatile country of 11 million where pensions have been cut 11 times since 2010.

Pollster Panagopoulos said he doubted the dual crisis would topple the government, but Tsipras might call another election — after two general elections and a referendum last year — if he felt in a deadlock.

CRISIS HOVERS OVER BREXIT

In mid-February, Greece briefly threatened not to sign off on final agreements at an EU summit on amending Britain’s membership terms unless Athens won assurances that EU states would not shut their borders. They did so anyway.

Now Tsipras has hinted at using the veto threat again to ensure his country does not become a holding pen for migrants.

“What I am seeking is the best possible outcome for Greece. Even if it means, to achieve that, using all tools provided for under (EU) conventions,” the leftist prime minister said in a television interview this week when asked if he could veto a deal between the EU and Turkey at a summit next week.

How Greece and the migrant crisis are handled may resonate at the other end of the continent in Britain, where voters will decide in a June 23 referendum whether to stay in the bloc.

James Ker-Lindsay, a Balkans expert at the London School of Economics, said leftist academics in Britain – a small but influential group typically supportive of the EU – were so dismayed by Brussels’ treatment of Greece in 2015 that it would not take much to alienate them completely.

“If it looks like a double dose harsh treatment, the euroscepticism which is coming in very strong from right-wing parties across the EU could start being repeated on the left, but for a very different reason,” Ker-Lindsay said.

(Writing by Michele Kambas; Editing by Paul Taylor and Mark John)