‘One out, one in’: EU and Turkey agree on broader Syrian migrant deal

European leaders said they have reached the outlines for a possible deal with Ankara to return thousands of refugees to Turkey and are hopeful a full agreement can be reached at a summit next week.

Turkey’s Prime Minister, Ahmet Davutoglu, outlined proposals early on Tuesday morning to resettle one Syrian refugee in Europe for every Syrian returned to Turkey from the Greek islands.

After 12 hours of talks in Brussels, the German chancellor, Angela Merkel, described the one in, one out proposal as “a breakthrough” that would deter refugees from making the perilous sea crossing to Greece, but said Europe needed more time to agree final details.

EU leaders will aim to seal the deal with Turkey at another summit on March 17-18.

However, the head of the UN refugee agency, Filippo Grandi, said he was “deeply concerned” by the proposed deal. “As a first reaction I’m 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,” said Grandi, head of the United Nations High Commissioner for Refugees (UNHCR), told the European Parliament on Tuesday.

The Turkish proposals, which had been agreed with Merkel and the Dutch Prime Minister, Mark Rutte, on the eve of the summit, came as a surprise to other EU leaders. One said EU officials were left scrambling to find out if it was “legally and logistically possible”, while another diplomat said it was “naive” to think that such a complex plan could be agreed so quickly.

David Cameron said the proposal to return all refugees who make it across the Aegean Sea to Greece could provide the basis of a settlement that would finally close the refugee trail through the Balkans. “It has been a long and difficult evening but I think we do have the basis for a breakthrough which is the possibility that, in future, all refugees who arrive in Greece will be returned to Turkey,” the UK Prime Minister said.

Following the summit, the European Union chief, Donald Tusk, said: “the days of irregular migration to Europe are over”.

Human rights groups say returning asylum seekers from Greece to Turkey would be illegal, but the EU is desperate to reduce the flow of migrants and refugees coming to Europe.

The German chancellor gave a strong signal that she supported doubling aid for Syrian refugees in Turkey, as the EU bargained with Ankara to do more to check the refugee influx.