Cameron heads for 'now or never' talks to keep Britain in EU

With all sides underlining that there is still work to be done to reach agreement at an EU summit in Brussels, there is also broad consensus that if the bloc fails to agree, they may never come up with a deal to help keep Britain from leaving.

Cameron is keen to end the week in Brussels with a deal that he can hail as a victory and then start campaigning to keep Britain inside the bloc before a referendum most officials expect will be held in late June.

Cameron, struggling to sell a deal to an increasingly skeptical British public and many in his own Conservative Party, has spent weeks touring European capitals to secure a deal, hold a referendum and put to rest the divisions over Europe that have dogged his party for years.

He has called for reform in four areas: measures to curb migration, safeguards to protect London's financial district from decisions binding the 19 members using the euro currency, for Britain to be excluded from "ever closer union" and for greater competition in the bloc.

And among the details, there will be debate over the wording of the safeguards for London's financial sector, on any commitment to future amendments of the bloc's founding treaties and on how long Britain can apply a measure to curb welfare payments for low-paid EU workers.

With a prospect of late-night talks on February 17, summit chairman Donald Tusk has scheduled what aides call an "English breakfast" on February 18 in hope of a final compromise.

"The negotiations are very advanced and we must make use of the momentum," he said in an invitation letter to EU leaders.

"There will not be a better time for a compromise."