EU leaders put the finishing touches to a contentious new plan to stem migration flows from Turkey to Europe, before submitting the document on Friday morning for consideration by Turkish Prime Minister Ahmet Davutoglu.
"Agreement on EU position," Luxembourg Prime Minister Xavier Bettel wrote on Twitter.
The plan is the bloc's latest effort to end a surge of migrants and asylum seekers that saw more than 1 million people reach European shores last year. Most crossed the Aegean Sea from Turkey to Greece, aiming to then move on to wealthy northern states.
The European Union hopes to strike a new deal Friday with Turkey to end uncontrolled migration across the Aegean, but the agreement has proven legally challenging and has met resistance in several EU capitals.
"The proposed package is very complicated, will be very difficult to implement, and it is on the edge of international law," Lithuanian President Dalia Grybauskaite warned as she arrived Thursday afternoon in Brussels for the start of a two-day EU summit.
But the EU leaders agreed a common position on the deal after eight hours of talks in the Belgian capital. Details were not immediately available.
Only "minor" changes had been made to the proposed agreement, a source said on condition of anonymity.
EU President Donald Tusk will present the proposal for the new deal Friday morning to Davutoglu. This could be followed by more negotiations among the 28 EU leaders if needed, the source said.
Tusk had said before the summit that he was "cautiously optimistic - but frankly speaking more cautious than optimistic" about finalizing the plan with Turkey this week. German Chancellor Angela Merkel said she agreed with his assessment.
The new deal, if accepted by Ankara, would centre on a migrant swap that would see the EU send Syrian asylum seekers from Greek islands back to Turkey, as part of a bid to undercut migrant smuggling networks. The approach has been slammed by human rights advocates as inhumane and illegal.
But the EU's position was strengthened Thursday after Europe's leading rights watchdog, the Council of Europe, endorsed the approach as long as asylum applications for those arriving on Greek islands are fully processed before any returns to Turkey.
Others remain sceptical. German refugee aid organization Pro Asyl said it is a "farce" to expect Greece to adequately process applications when it has a "de facto non-existent asylum system."
Dutch Prime Minister Mark Rutte predicted that the migrant swap, which would see the EU resettle Syrians directly from Turkey, would halt the flow of migrants across the Aegean "in three to four weeks."
Davutoglu rejected domestic criticism that the plan would turn Turkey into a giant refugee camp.
"That is out of the question," he said before leaving for Brussels late Thursday, according to the Turkish news agency Anadolu.
Cyprus had been considered one of the biggest potential stumbling blocks for the new migrant deal, after Turkey asked for the agreement to include quick progress on its long-running EU membership bid.
Cypriot President Nicos Anastasiades has insisted that Turkey first implement past obligations that would, for instance, allow Cypriot vessels to enter Turkish ports, despite the long-standing tensions between the two sides.
"It's so easy - if Turkey will fulfill its obligations ... then there is no problem. But without it, we could do nothing," Anastasiades said as he arrived for the summit.
EU leaders are only expected to promise Turkey that they will "prepare" for the opening of new negotiating chapters. Irish Prime Minister Enda Kenny said it is "unlikely that the accession chapters will be expedited."
A Turkish quest to have its citizens get visa-free access to Europe by June is proving sensitive. The EU is expected to continue insisting that Ankara first meet prerequisites.
"It is clear that we won't start haggling about the conditions of visa liberalization," Rutte said. "They want to speed it up? Fine, but they have to show they can speed up, too, to meet the 72 benchmarks."