European officials have said that they were not certain when a dinner meeting between Theresa May and Jean Claude Juncker was going to happen even as late as Friday last week.

A spokesman for the European Commission said the idea had been “on the agenda for a long time”, but the date ahead of a critical European Council meeting was not confirmed until the last few days.

At the same time Ms May’s spokesperson told reporters the dinner had been in her diary for weeks, as Number 10 denied claims it was a last-minute attempt to break a deadlock in Brexit negotiations ahead of the Council.

Foreign Secretary Boris Johnson urged European leaders on Monday to start negotiating on future trade with Britain, after EU negotiators said last week there had not been “sufficient progress” to do so.

Explaining how the dinner was scheduled three days ahead of the crunch European Council, Mr Juncker’s spokesman said: “It wasn't announced because although it was on the agenda for a long time, we agreed that it would be announced when we had a confirmed date suitable and compatible with the agendas of the Prime Minister and the President.

“That’s why it wasn't announced earlier, or last Friday, but when we became sure that it would take place, and when it was announced simultaneously in London and in Brussels.”

Around the same time in Westminster, Ms May’s spokesman was asked whether the dinner had been “shoehorned” in ahead of the Council meeting starting on Thursday.

Brexit: the deciders Show all 8 1 /8 Brexit: the deciders Brexit: the deciders European Union's chief Brexit negotiator, Michel Barnier Getty Brexit: the deciders French President Emmanuel Macron Getty Brexit: the deciders German Chancellor Angela Merkel Reuters Brexit: the deciders Commission President Jean-Claude Juncker EPA Brexit: the deciders The European Parliament's chief Brexit negotiator Guy Verhofstadt Getty Brexit: the deciders Britain's Prime Minister Theresa May Getty Images Brexit: the deciders Britain's Chancellor of the Exchequer, Philip Hammond PA Brexit: the deciders After the first and second appointed Brexit secretaries resigned (David Davis and Dominic Raab respectively), Stephen Barclay is currently heading up the position PA

On whether it was a “panic” attempt to try and move things forward, her spokesman said: “This is part of a wider programme of engagement, which you have seen in recent weeks and will continue to see going forward.

“We’ve always said we want Britain leaving the European Union to be a smooth process and this is part of achieving that.”

He later said that it had been arranged since “around” the time of Ms May’s Florence speech last month.

It comes as the EU council is preparing to confirm that it believes there has not been sufficient progress in Brexit talks to begin discussing future trade now.

Mr Juncker and the Commission’s chief negotiator Michel Barnier said after the fifth round of Brexit talks finished last week, that they would recommend more progress is needed on withdrawal terms, including the divisive issue of Britain’s ‘divorce bill’.

In London, Ms May is under pressure from hardline Brexiteers to make no further concessions and to walk away from talks if trade is not being discussed by Christmas.

Arriving for a meeting of EU foreign affairs ministers in Luxembourg, Mr Johnson said: “We think in the UK that it's time to get on with these negotiations.

Jean-Claude Juncker: Brexit will take longer than initially thought

“It's ready for the great ship to go down the slipway and on to the open sea and for us to start some serious conversations about the future and the new relationship.”

Ms May was also expected to speak by phone on Monday to French President Emmanuel Macron and Irish Taoiseach Leo Varadkar before departing for Brussels for the dinner, due to start at 5.30pm UK-time and last 90 minutes.

The dinner will also be attended by Brexit Secretary David Davis, Downing Street aide Ollie Robbins, Mr Barnier and Mr Juncker’s Head of Cabinet, Martin Selmayr.

Mr Selmayr was widely blamed for leaking details of a previous private dinner at Number 10 in April, when Mr Juncker reportedly said he left “10 times more sceptical” about Brexit than when he arrived.

The leak led to an angry response from Ms May on the steps of Downing Street in which she warned that “there are some in Brussels who do not want these talks to succeed”.