British Foreign Secretary Philip Hammond says there will be "very big issues" still on the table at a European Union summit this week as leaders try to thrash out a deal to keep Britain in the 28-nation bloc.

Hammond said Monday that "there are lots of things still being discussed" about reforms the EU might undertake to satisfy the government in London.

Prime Minister David Cameron will visit French President Francois Hollande late Monday after meeting with his German counterpart Angela Merkel on Friday. Cameron wants to hold a referendum by the end of next year on whether Britain should leave the EU. If a deal is clinched at the summit, he might call a vote as soon as June.