Britain and the European Union (EU) reached agreement in only one of the four areas where Prime Minister David Cameron wants to see reform, a source close to the negotiations said on Sunday.
Cameron had dinner with European Council President Donald Tusk in London on Sunday to try to agree the main points of Britain's renegotiation over its relationship with EU before a summit of leaders on Feb. 18-19.
Reaching an agreement on the UK's relationship with the EU at the February summit is seen as key to Cameron's ability to put the UK's membership of the EU to a public vote before the summer parliamentary recess.
The two had been been discussing the EU's proposal for an emergency brake on benefits payments to migrants as a way to meet Cameron's target of curbing immigration into Britain.
The UK also wants the ability to opt out of further political integration into the EU, more powers for national parliaments to block EU legislation and recognition that the euro is not the only currency of the bloc, as well as guarantees the UK would not have to contribute to euro zone bailouts.
Cameron has been criticized in the UK for the speed at which his government has dealt with the influx of migrants.
After the talks, Tusk said there had been no deal and that there would be another 24 hours of discussions. After the talks are finished, Britain is expected to release a text of the draft renegotiation terms.
- CNBC contributed to this report.