THE European Union without Britain is "impossible", Matteo Renzi, the Italian Prime Minister has insisted following a meeting with David Cameron.

But as the Prime Minister continued to cut a diplomatic dash across the continent, Dara Murphy, the Irish Foreign Minister, revealed Dublin had already started making contingency plans to deal with a possible British exit.

Today, Mr Cameron will continue to discuss his plans for reforming the EU with Enda Kenny during the Irish Taoiseach's visit to Downing Street.

Mr Murphy said: "The core focus at the moment is the strategy around negotiation to play a part in keeping the UK in the European Union. But, yes, it would be remiss of us given the possibility that our largest trading partner may be exiting the European Union, that is something we, of course, are looking at."

Earlier, the PM said that he and Mr Renzi had had "very good discussions" on "the importance of reform and change in Europe where we do have some common perspectives and some common ideas on the need for competitiveness, for flexibility".

Mr Cameron later flew to Luxembourg for a working dinner with the country's Prime Minister Xavier Bettel.

With further trips to Slovenia and Slovakia today and tomorrow, as well as meetings in London with not only Mr Kenny but also European Parliament President Martin Schulz, Downing Street expects the PM to have spoken to more than 20 EU leaders by the end of the week.

The UK Government's demand for renegotiation of the terms of Britain's EU membership is on the agenda for next week's Brussels summit, although the meeting is likely to be dominated by the economic crisis in Greece.