BORIS Johnson is holding up the Brexit talks by stopping Theresa May making an acceptable offer on Britain’s "divorce bill", an ally of German chancellor Angela Merkel has said.

Michael Fuchs, Deputy Chairman of Mrs Merkel's CDU/CSU group in the German parliament, said he thought the Prime Minister would bring forward proposals on Britain's financial obligations that could break the deadlock in negotiations if she was not plagued by "internal trouble" in the Conservative Party.

He said Mrs May's proposal in her Florence speech last month that Britain would pay contributions to the Brussels budget agreed in 2014 and which runs to 2020 of around £18 billion did not go far enough, as it did not include an offer to pay the pensions of EU bureaucrats; thought to run to billions of pounds.

Mr Fuchs spoke after the PM attended a working dinner in Brussels with Jean-Claude Juncker, the European Commission President, and Michel Barnier, the EU’s chief negotiator, which offered little sign of tangible progress.

While they agreed to "accelerate" efforts to find a Brexit deal, there was no indication the EU side was ready to revise its view that the talks still had not made sufficient progress for them to move forward to the second phase - including a free trade deal - with Britain's divorce bill a key stumbling block.

Mr Fuchs told BBC Radio 4's Today programme: "You have to accept that there are a lot of things to be paid. Let me just say: pensions, which is not solved.

"This problem has to be solved and the UK has to come up with decent proposals."

Asked about the offer in Mrs May's Florence speech, he replied: "It's not a decent proposal; it's a proposal but it's not enough."

Turning his fire on the Foreign Secretary, he went on: "I know there are internal problems; whatever she is offering, Boris Johnson is saying it's too much.

“I don't know what his influence[is]; it seems to be pretty strong because otherwise she would come up with other proposals I guess and the problem is she has internal trouble in the Tories."

But asked if Mr Johnson should be sacked, Mr Fuchs replied: "Of course not.

"I am critical because [of]what he said: not a single cent to the EU. It's, of course, not acceptable because you know what kind of duties you have; I mean it's all on the table."