British Prime Minister David Cameron met today with French President Francois Hollande after EU chief Donald Tusk warned there was a "real" danger of the 28-nation bloc breaking up over a "Brexit".

As Cameron arrived in the French capital to discuss Britain's EU renegotiation ahead of a key summit this week, Tusk warned Europe was at a "critical moment".

"It is high time we started listening to each other's arguments more than to our own," Tusk said during a visit to Romania to discuss Britain's membership of the European Union.

The EU is trying to broker a series of reforms to Britain's relationship with the bloc ahead of a looming "in-out" referendum on EU membership that could be held in the UK as early as June.

British officials hope a deal can be nailed down at a summit in Brussels on Thursday and Friday that could prevent the possibility of Britain exiting the EU.

In London, Cameron's spokeswoman said: "We have made progress (on renegotiation) but there's details to be pinned down.

"Nothing is agreed until everything is agreed," she added.

A deal could pave the way for a referendum on whether Britain should leave the EU or stay in and with it Cameron could support remaining in the bloc.

But some of Cameron's demands are proving problematic to his European partners.

Analysts say France — which with Germany is considered the EU's engine — is likely to want to see changes in what is being proposed over economic governance.(AFP,PTI)