Prime Minister David Cameron said on 18 February that he expected negotiations with fellow European leaders to be tough, but that he would not accept a deal at any price to keep Britain in the EU. Cameron made the comments as he arrived at a crunch summit in Brussels where he will try and achieve concessions on key issues he believes are vital if he is to win an EU membership referendum.

"We've got some important work to do today and tomorrow and it's going to be hard. I'll be battling for Britain. If we can get a good deal, I'll take that deal, but I will not take a deal that does not meet what we need. I think it's much more important to get this right than to do anything in a rush, but with goodwill, with hard work, we can get a better deal for Britain," he said.

Diplomats predict that negotiations will run late through the night and into Friday as Cameron faces opposition to his plans on welfare payments, concessions to non-Eurozone members and the EU's commitment to "ever closer union".