Migrant crisis: EU agrees joint position to put to Turkey
Xavier Bettel said the common EU position would be put to Turkish PM Ahmet Davutoglu on Friday morning.
The proposed deal would see all migrants travelling to Greece from Turkey sent back.
In return it is thought the EU might offer Turkey financial aid and visa-free access to Schengen countries.
German Chancellor Angela Merkel said that Turkey had to meet international standards of protection for all migrants, Reuters reports.
She said that the legal resettlement of Syrian refugees direct from Turkey, which forms part of the deal, could start a few days after the first returns from Greece.
Lithuanian President Dalia Grybauskaite has warned that the plan to return people to Turkey is "on the edge of international law" and difficult to implement.
Mr Davutoglu has said he will not accept Turkey becoming an "open prison" for migrants.
To meet concerns over the plan's legality, the leaders discussed providing assurances that each person claiming asylum will be given a full hearing in Greece, the BBC's Damian Grammaticas reports from Brussels.
