JEAN-CLAUDE Juncker has voiced concerns about the "stability and accountability" of David Davis and his political mandate to conduct the Brexit talks, new documents have revealed.

In talks with chief EU negotiator Michel Barnier, Mr Juncker said the Brexit Secretary's "apparent lack of involvement" in talks "risked jeopardising the success of the negotiations", according to official minutes released in Brussels.

An official Commission spokeswoman declined to comment on the minutes, saying the situation had "moved on" since July 12, when Mr Barnier briefed Mr Juncker and other commissioners.

Mr Juncker's comments emerged as Mr Barnier released a raft of new papers setting out the EU's negotiating position on sensitive issues including the future of the Irish border, customs arrangements, intellectual property rights, public procurement and data protection.

The minutes of the July 12 meeting at the Commission's Berlaymont HQ recorded that Mr Juncker "expressed his concern about the question of the stability and accountability of the UK negotiator and his apparent lack of involvement, which risked jeopardising the success of the negotiations".

In an apparent reference to the Conservative Government's loss of its overall majority in the June General Election, the minutes added that Mr Juncker urged Mr Barnier "not to accept discussions at the purely technical level with negotiators who had no political mandate, while fundamental political questions still remained".

The official minutes came as new papers from Brussels made clear the Commission puts the responsibility for sorting out arrangements for the Irish border after Brexit solely on Theresa May’s Government

The documents made clear they were not putting forward solutions to the issue of the Irish border, stressing how the onus for this was on the UK.

The EU papers called for "unique solutions" and floated the possibility of "specific provisions" being included in the exit agreement to address the fact the peace process was underpinned by common EU law.

They stressed that nothing in Britain's withdrawal deal should affect Ireland's place in the single market and customs union and that people should be allowed to continue to cross the Irish border to work, study and receive medical treatment.

Meanwhile, Antonio Tajani, the President of the European Parliament, said he would ask the European Council to postpone its assessment of whether or not "sufficient progress" had been made to move on to trade talks from October to December.

Mr Tajani's comments came as former European Council President Herman van Rompuy warned that chances of sufficient progress being made by October were "in the neighbourhood of zero".

But Damian Green, the First Secretary of State, described Mr van Rompuy’s remarks as “too pessimistic” and pointed out there were several rounds of talks to go.

“Let's see what happens between now and October," he added.