BRUSSELS (AP) — The Latest on EU summit on changes demanded by Britain (all times local):
EU President Donald Tusk says talks between Britain and the 27 other European Union nations have made "some progress, but a lot remains to be done."
Tusk spoke after a 15-hour day in which EU leaders discussed Britain's goal of a new deal with the bloc, and the unfolding migrant crisis.
British officials said the first session of talks had not closed gaps on all issues, and "there's a lot of hard work to do overnight."
EU leaders are due to reconvene at breakfast Friday for more talks
European leaders' first working session in Brussels has ended without a breakthrough on how to redefine Britain's relationship in the 28-nation bloc.
A British official says there's no "sense that gaps in key issues had narrowed ... there's a lot of hard work to do overnight." The official was speaking on condition of anonymity to discuss the closed-door talks.
Another European official said a main source of tension was the length of time that Britain's limit on welfare benefits for EU workers would last. The Czech Republic is opposing the U.K.'s goal of a seven-year freeze.
The leaders are discussing Europe's migration crisis over dinner Thursday night before returning to the subject of Britain's renegotiation of its relationship with European Union.
French President Francois Hollande is warning European leaders against making too many concessions to Britain as it debates whether to stay in the European Union.
Speaking upon arrival at an EU summit Thursday in Brussels, Hollande said that could prompt other countries to seek "special rules" and undermine the principles of European unity.
Hollande said, "I want Britain to stay in the EU. But I hope most of all that Europe can advance, can be stronger, and that no chief of state could stop that."
He said that at this summit, "It's the European Union in question, not just one country."
German Chancellor Angela Merkel says she wants to do everything to help ensure that Britain remains in the European Union.
Merkel said as she arrived Thursday at a summit of EU leaders that some issues remain to be cleared up but added: "I'm going into this debate with the position that we would like to do everything to create the conditions so that Great Britain can remain part of the European Union."
Merkel said that "this is important from the German point of view."
European Union President Donald Tusk says Thursday's summit of the 28 EU leaders to decide on the reforms that British Prime Minister David Cameron is calling for will be one of the most important the bloc has seen.
With many core issues still outstanding going into the two-day summit, Tusk said hours ahead of the opening summit session: "One thing is clear to me though. This is a make or break summit, I have no doubts."
Tusk said that both sides were still "in the middle of still very difficult and sensitive negotiations," as the summit center not only started filling with leaders but also legal experts who would have to pour any decision into binding legal texts.
Prime Minister David Cameron says he'll be "battling for Britain" but still faces hurdles in his talks on a deal with the European Union.
Arriving at an EU summit in Brussels, Cameron said he was fighting to close a deal by Friday, but "it's going to be hard."
He said that "if we can get a good deal I'll take that deal, but I will not take a deal doesn't meet what we need. I think it's much more important to get this right than to do anything in a rush."
Cameron hopes the 28 EU nations can strike agreement on the changes Britain seeks to its relationship with the bloc, so he can call a referendum on U.K. membership for as early as June.