British Prime Minister David Cameron has got closer to carrying out a difficult reform deal with the EU leaders but warned that there would be hard work to seal an accord by February as hoped.

Cameron outlined his plans at a summit in Brussels on Thursday and appealed to the leaders to work with him on his demands including a freeze on benefits for EU migrants, before he holds a referendum on a possible "Brexit" by the end of 2017.

"Really good progress has been made but it is going to be tough… nothing is certain in life or in Brussels but there is a pathway to a deal in February," Cameron told reporters at a news conference.

EU President Donald Tusk said the EU leaders agreed to work for a compromise despite reservations over Cameron's reforms after what he described as a "make or break" summit at the end of a crisis-filled year.

"I am far more optimistic than before the meeting," Tusk, told a news conference.

The turnaround came just hours after both Tusk and French President Francois Hollande warned Cameron that his migrant benefit demands were "unacceptable".

Cameron's other reform demands are far less problematic for his counterparts. The demands include protections for countries that are not in the eurozone, an exemption from more EU integration and greater economic competitiveness.

EU membership has long been a hot topic in Britain. Eurosceptics, who believe the UK would be better off outside the political and economic union, seek the UK's withdrawal from the EU. Various polls have indicated that the British public is divided on the issue.