LONDON (Reuters) – Donor nations pledged on Thursday to give billions of dollars in aid to Syrians as world leaders gathered for a conference to tackle the world’s worst humanitarian crisis, with Turkey reporting a new exodus of tens of thousands fleeing air strikes.

With Syria’s five-year-old civil war raging and another attempt at peace negotiations called off in Geneva after just a few days, the London conference aims to address the needs of some 6 million people displaced within Syria and more than 4 million refugees in other countries.

Underlining the desperate situation on the ground in Syria, Turkish Prime Minister Ahmet Davutoglu told the meeting that tens of thousands of Syrians were on the move toward his country to escape aerial bombardments on the city of Aleppo.

“Sixty to seventy thousand people in the camps in north Aleppo are moving toward Turkey. My mind is not now in London, but on our border – how to relocate these new people coming from Syria?” he said. “Three hundred thousand people living in Aleppo are ready to move toward Turkey.”

Turkey is already hosting more than 2.5 million Syrian refugees. Jordan and Lebanon are the other countries bearing the brunt of the Syrian refugee exodus.

Several speakers said that while the situation of refugees was bad, that of Syrians trapped inside the country enduring bombardments, sieges and, in some places, starvation was far worse.

“With people reduced to eating grass and leaves and killing stray animals in order to survive on a day-to-day basis, that is something that should tear at the conscience of all civilized people and we all have a responsibility to respond to it,” U.S. Secretary of State John Kerry told the conference.

A U.N. envoy halted his attempts to conduct Syrian peace talks on Wednesday after the Syrian army, backed by Russian air strikes, advanced against rebel forces north of Aleppo, choking opposition supply lines from Turkey to the city.

Kerry told the conference he had spoken to his Russian counterpart Sergei Lavrov about the situation.

“We have agreed that we are engaged in a discussion about how to implement the ceasefire specifically as well as some immediate, possible confidence-building steps to deliver humanitarian assistance,” he said.

In a blunt attack on Russia, Turkey’s Davutoglu told a news conference that those supporting Syrian President Bashar al-Assad’s forces were committing war crimes and called on the United States to adopt a more decisive stance against Russia.

EDUCATION, JOBS

United Nations agencies are appealing for $7.73 billion to cope with the Syrian emergency this year, and countries in the region are asking for an additional $1.2 billion.

Conference co-hosts Britain, Norway and Germany were the first to announce their pledges, followed by the United States, the European Union, Japan and other nations.

Britain and Norway promised an extra $1.76 billion and $1.17 billion respectively by 2020, while Germany said it would give $2.57 billion by 2018. The United States said its contribution this fiscal year would be $890 million.

The almost five-year-old conflict has killed an estimated 250,000 people and stoked the spread of Islamist militancy across the Middle East and North Africa.

For European nations, improving the humanitarian situation in Syria and neighboring countries is crucial to reducing incentives for Syrians to travel to Europe.

U.N. Secretary General Ban Ki-moon said the first steps in the Geneva peace talks had been undermined by a lack of sufficient humanitarian access and by a sudden increase in aerial bombing and military activity on the ground.

“The coming days should be used to get back to the table, not to secure more gains on the battlefield,” he said.

The conference will focus particularly on the need to provide an education for displaced Syrian children and job opportunities for adults, reflecting growing recognition that the fallout from the Syrian war will be very long-term.

(Additional reporting by Andreas Rinke and Arshad Mohammed, writing by Estelle Shirbon; Editing by Mark Heinrich and Raissa Kasolowsky)