© Matt Dunham/PA David Cameron
France has accused David Cameron of trying to "dismantle" the European Union and suggested it will block his plans to claw back powers from Brussels.
Laurent Fabius, the French foreign minister, said that the referendum on Britain's membership of the EU is "very risky" and "quite dangerous".
He said that Britain had "joined a football club" and cannot decide "in the middle of the match that they want to play rugby".
Mr Cameron will on Friday travel to Germany where he will warn Angela Merkel, the German Chancellor, that Britain will vote to leave the EU unless it agrees to meet his demands.
It follows reports that France and Germany have agreed a pact which will enable closer integration in Europe without treaty change, in a significant blow to Mr Cameron's plans.
Philip Hammond, the foreign secretary, issued an emphatic warning to EU leaders. He told BBC News : "We’re confident that our counterparts in Europe understand that if these issues are not addressed, the British people will not give their endorsement to the proposition that Britain should remain part of the European Union.”
Mr Cameron will on Friday travel to Warsaw to meet he Polish Prime Minister before concluding a two-day diplomatic offensive by meeting Angela Merkel, the German Chancellor, in Berlin.
On Thursday he met Mark Rutte, the Dutch Prime Minister, and Francois Hollande, the French President.
It has also emerged that Mr Cameron will be able to use the full weight of the the government to support his campaign for Britain to stay in a reformed EU.
There will no period of purdah in the run up to the referendum, meaning that departments like the Treasury and the Foreign Office will be able to produce reports supporting the case for Britain to stay in the EU.
During the run up to the referendum on Scottish independence, the government was banned from publishing material that argued "for or against any outcome".
The EU referendum bill, however, makes clear that restrictions on publishing "promotional material" will not apply in the run up to the historic vote.
The legislation infuriated Tory Eurosceptics, who fear it will mean that their case for leaving the EU will not get a fair hearing from the British public.
Nigel Farage, the Ukip leader, warned that "Cameron's EU referendum bill doesn't guarantee a fair vote".
Downing Street has said that Mr Cameron will seek treaty change to secure welfare reforms, an approach confirmed by Mr Hammond.
Mr Hammond told BBC Radio 4's Today programme: “The Prime Minister’s made clear that some of the demands that we are making will require treaty change to make them irreversible and substantive and make them proof against challenge in the European courts. Many other parts of the agenda will not require treaty change, but some of them will."
Mr Rutte told Mr Cameron during their meeting that the Dutch will "work to find solutions that could benefit everyone across the European Union."