Turkey has hailed an agreement with Europe to help ease the migrant crisis as a "historic day."
Under the Brussels deal, refugees and migrants making the dangerous crossing from Turkey to Greece after Sunday will be returned and placed in a camp. It effectively closes Europe's border.
In return, the EU will take in thousands of Syrian refugees directly from Turkey and reward it with more money, early visa-free travel and faster progress in EU membership talks.
Migrants who arrive in Greece from Sunday will be subject to being sent back once they have been registered and their individual asylum claim processed.
The returns are to begin on April 4, as would resettlement of Syrian refugees in Europe
ITV News Deputy Political Editor Chris Ship reports:
The agreement involves closing the EU border on March 20 and sending back migrants who arrive in Greece after that date to Turkey.
Cameron asks EU leaders to back deployment of more international patrol ships close to Libyan coast in bid to deter migrant smugglers.
David Cameron will tell his European colleagues that the migration route from Libya to southern Italy is about to begin once more.