JEAN-Claude Juncker has thanked Britain for its efforts during the Second World War but insists “now they have to pay”.

In remarks that will do little to help ease the tense atmosphere hanging over the Brexit talks, the European Commission President likened the situation to paying a bar bill.

“If you are sitting in a bar and ordering 28 beers and then suddenly one of your colleagues is leaving and is not paying, that is not feasible. They have to pay,” he said.

Just days before the next European Council summit, Mr Juncker made clear the Brexit process would take "longer than we initially thought", blaming delays on Britain's failure to settle its financial obligations.

Speaking to students at the University of Luxembourg, Mr Juncker declared: "They have to pay, they have to pay, not in an impossible way. I'm not in a revenge mood. I'm not hating the British. The Europeans have to be grateful for so many things Britain has brought to Europe before war, during war, after war. But not they have to pay."

He was speaking after Michel Barnier said talks on issues including the divorce bill had not made sufficient progress for him to be able to recommend moving on to the second phase of negotiations, covering trade.

The EU’s chief negotiator said the financial settlement had not even been the subject of negotiations during four days of talks this week because the UK was not prepared to indicate how much it was willing to pay.

However, a leaked document suggested that EU leaders meeting at the European Council summit next week could authorise "internal preparatory discussions" on the shape of a future trade relationship and a transition deal, in a move which could offer Theresa May hope for talks by the end of the year.

In response to Mr Juncker’s comments, Iain Duncan Smith, the former Conservative leader, was scathing, saying: “Well, first of all, Mr Juncker knows a little bit more about the bar than many of us do.

"But I have to say that the idea that it's as simplistic as ordering a pint of beer and then not paying for it is quite ridiculous,” declared the Scot.

He pointed out how the UK Government had offered to pay what it was “due legally; what it is bound to do and fulfil its commitments,” but he stressed how the Brussels negotiations were “not some kind of horse trading exercise that says: ‘Look, you offer a bit more and we'll offer a bit of this.’”

Tom Brake for the Liberal Democrats claimed the Tory Government's internal battles were weakening the Government’s hand in Europe.

But he added there was a “glimmer of light at the end of the tunnel” after Donald Tusk, the European Council President, suggested possible trade talks in December.

“This is the signal for the UK Government to make a convincing offer on EU citizens' rights, the financial settlement and provide clarity over the Northern Ireland border," he added.

Meanwhile, No 10 denied suggestions there had been a delay in bringing the EU Withdrawal Bill back to the Commons for its detailed committee stage because Theresa May was frightened some Tories might back certain amendments and defeat the Government.

The Prime Minister’s spokeswoman said: “We had not fixed a date or announced it to the House. As the Leader made clear to the House yesterday there are hundreds of amendments and 54 new clauses and it’s right that we take time to closely evaluate those and that’s what we are doing.

“The process is that the Leader updates the House on business and that is what she will do when we are ready to bring this to committee stage,” she added.