British Prime Minister David Cameron remains locked in talks with leaders in Brussels, over his EU reform demands.
One official says they have hit “critical” snags.
“We made some progress, but there is still no deal and, as I have said, I will only do a deal if we get what Britain needs,” said Cameron, heading back into talks on Friday.
“So we are going to get back there. We are going to do some more work, and I will do everything I can.”
There have been all night talks and a series of private meetings.
Cameron is aiming to seal a deal to use to campaign for Britain to stay in the EU, in a planned membership referendum, which could take place in June.
Financial safeguards and migration curbs have proved to be contentious issues.
“During the night there were some proposals exchanged between us, notably concerning France,” said French President Francois Hollande.
“There is the will to have a financial regulation which can be applied to all financial capitals of Europe, and there is no right to veto.”
Meanwhile, Greece is threatening not to sign off on the final conclusions of the summit in Brussels, which is also tackling migration.
Athens is said to be holding out for assurances that EU states will not shut borders.
Reporting from Brussels, euronews’ Sandor Zsiros said: “According to an EU diplomat, leaders will try to iron at remaining differences at tonight’s dinner – and a Britain deal is still possible.
“In the meantime, the European Council has asked delegations of member states to extend hotel bookings for tonight.”