European Union leaders say they are edging closer towards a deal with Turkey to ease the migration crisis, but have delayed a final decision.
Turkey has offered to take back migrants who have passed through its country and continued to Europe.
EU leaders say they're confident a full agreement could be reached at a summit next week.
After late night talks at an emergency summit in Brussels, the British Prime Minister David Cameron could see the basis for a breakthrough.
"...which is the possibility that in future, all migrants who arrive in Greece will be returned to Turkey. Now that would, if implemented, break the business model of the people smugglers and end the link between getting in a boat and getting settlement in Europe. Now that is something I've been arguing for a year and I think this is significant but only if it's fully implemented and that's what needs to happen next that will make a real difference."
For each migrant that's returned to Turkey the country wants the EU to accept a Syrian refugee on a one for one basis and offer more funding and progress for EU integration.
As part of the efforts to counter people smuggling NATO has sent ships to Turkish and Greek waters in the Aegean Sea.
Turkey's prime minister, Ahmet Davutoglu, says the ships will help.
"This is a humanitarian operation, not a military operation, but we need the capacity of NATO in order to prevent new refugees, children dying in such an adventurous journey. Therefore Frontex on one side, NATO on the other side, Turkish and Greek capacity also, together we want to prevent this waves of refugees and also the tragic events in the Aegean Sea."
EU leaders have also declared the main Balkan migrant route closed, after the Former Yugoslav Republic of Macedonia, backed by Austria, Croatia, Slovenia and Hungary, limited border crossings to a trickle.
Turkey is also seeking to leverage the migration deal to bring it closer to gaining membership of the EU.
European Parliament President Martin Schulz raised the issue of freedom of the press, considered a principal value of the European Union, with the Turkish Prime Minister.
His intervention was prompted by news Turkish authorities has seized control of the Zaman newspaper, the country's top-selling newspaper, last week, at the request of an Istanbul prosecutor.
"We raised the internal situation in Turkey. I had a very open exchange with the Prime Minister who disagreed with my point of view. I think this is not a surprise. I insisted that for the European Parliament and the European Union, freedom of media is a key element of our European identity. The Prime Minister explained from his point of view the case, I took not about the explanation of the Prime Minister."
Europe is dealing with its biggest refugee crisis since World War Two.
Last year, more than a million people entered the EU by boat mainly by going from Turkey to Greece.
Share
