(Reuters) – European Council President Donald Tusk has stressed in a note to EU leaders that a planned deal with Turkey to stem the flow of migrants to Greek islands will be a “temporary and extraordinary measure”.

The note, seen by Reuters, lays out principles for an agreement that Tusk hopes to conclude when he chairs a summit of EU leaders on Thursday followed by a meeting of EU leaders with the Turkish prime minister in Brussels on Friday.

It stresses the need for asylum seekers landing in Greece to be returned to Turkey only after their claims are reviewed under EU law and that Turkey will protect them.