STRASBOURG (Reuters) – “Alarming” numbers of migrants are reaching Libya to cross the Mediterranean, a senior EU official said on Wednesday, adding a warning that Italy must be ready for them to avoid new border chaos inside Europe.

“The numbers of would-be migrants in Libya are alarming,” European Council President Donald Tusk told the European Parliament a day after Austria said it planned tighter controls on its Italian border in anticipation of a summer migrant surge.

Noting that anarchy in Libya ruled out for now the kind of deal made with Turkey to block what was last year’s main route into Europe via Greece, Tusk said EU allies must be ready to help manage new arrivals within Italy, as well as on Malta.

But in referring to last year’s chaotic movement of nearly a million people from Greece that saw EU states closing borders with each other, threatening the bloc’s cherished Schengen zone of passport-free travel, Tusk warned of a similar threat if Italy and its EU partners did not cooperate to contain flows.

“As regards the Balkan route, we undertook action much too late, which resulted among others in the temporary closure of the borders inside Schengen,” he said of the many months it took to enforce EU rules obliging asylum seekers to remain in Greece.

“This is why our full cooperation with Italy and Malta today is a condition to avoid this scenario in the future.”

Austria, which with France and Germany has long complained that Italy simply “waves through” migrants heading north, has said it expects double last year’s 150,000 to reach Italy and will tighten controls on the Brenner Pass frontier.

Rome has rejected criticism but some EU diplomats are concerned that Italy, which saw arrivals fall last year, may not be able or willing to accommodate a new surge and to hold people while asylum claims are assessed, as Greece is now doing.

Nearly 10,000 people reached Italy last month, compared to fewer than 2,300 in March 2015, U.N. data shows. Arrivals in Greece from Turkey have fallen significantly since Ankara agreed to take back all migrants, including Syrian refugees. Reaching Italy is much riskier than Greek islands off the Turkish coast.

European Commission President Jean-Claude Juncker told the same parliamentary session that implementing the EU-Turkey deal remained a “Herculean task”, for practical reasons as well as disputes with Ankara over human rights.

In rare public rebuke to Turkish President Tayyip Erdogan, whom Brussels has assiduously courted in seeking his help to curb migrant flows, Juncker criticized Ankara’s summoning of the German envoy to complain that Erdogan was mocked on German TV.

“I simply cannot comprehend that a German ambassador should be summoned over an admittedly outrageous satirical song,” Juncker said. “This does not bring Turkey any closer to us but rather drives us further apart.”

Among incentives for Turkey to take back migrants from Greece is a pledge to revive talks on Turkish EU membership.

(Writing by Gabriela Baczynska; Editing by Alastair Macdonald and Alison Williams)