MICHEL Barnier has dismissed UK pleas for parallel talks to be held with the European Union over withdrawal from the bloc and a future trade deal.

The EU’s chief negotiator expressed growing frustration with the UK Government over the state of the Brexit negotiations ahead of the next round of talks in Brussels.

In a series of tweets aimed at Theresa May and David Davis, Barnier insisted talks must first focus on financial obligations, citizens rights and the Irish border, before any future trade arrangement could be discussed.

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Taking to the social media platform, he posted: “3rd round of #Brexit negotiations with #UK begins next week. Focus on orderly withdrawal. #EU positions clear and transparent since day one.”

He went on to list each of the nine so-called “position papers” published by the European Commission earlier this summer.

The development came as the UK Government published two more of its own position papers – on goods on the market and the confidentiality of documents – and announced that more will follow throughout the week.

Barnier’s intervention was a response to renewed calls over the weekend by Brexit Secretary Davis in which he called again for talks on a future UK trade deal with the EU to be held at the same time as the UK negotiates its withdrawal from the bloc.

Davis wants talks over a deal to start at the October meeting of the EU Council, but Brussels has repeatedly emphasised that agreement must be reached on the UK’s financial settlement, the Irish border and citizens’ rights before discussions can turn to the UK’s future relationship with the bloc. Writing in the Sunday Times, Davis said: “I firmly believe the early rounds of the negotiations have already demonstrated that many questions around our withdrawal are inextricably linked to our future relationship. Both sides need to move swiftly on to discussing our future partnership, and we want that to happen after the European Council in October.”

A spokeswoman for Theresa May said: “We’re confident that we’ll have made sufficient progress by October to be able to advance talks to the next phase. That’s what David Davis said at the weekend and that’s our aim and we’re confident that we’re working at pace and will be able to get to that point.

“The Prime Minister’s view is that both sides need to demonstrate a dynamic and flexible approach to each round of the negotiations. We want to be able to move on to the next stage by European Council in October and that’s our aim.”

Meanwhile, the UK Government yesterday insisted there was no possibility of remaining within the EU customs union post-Brexit.

Northern Ireland Secretary of State James Brokenshire said that to do so would prevent the UK from negotiating international trade deals. However, he told businesses across the island of Ireland that there would be a period of implementation where the UK would adhere closely to the existing customs union.

Speaking following a meeting with the Irish and British Chamber of Commerce in Dublin, Brokenshire said businesses had voiced their “desire for certainty, not wanting to see cliff edges, sudden shifts.”

“We think it is important there is an implementation period where the UK would adhere closely to the existing customs union,” said Brokenshire.

“But ultimately it is about the UK being able to negotiate international trade deals. We want to harness those freedoms. If we were to remain in the customs union that would prevent us from doing so.

“We are leaving the EU, customs union and single market. We have set out options as to how we can achieve that frictionless trade,” he added.

Divisions over Brexit continue to plague the Cabinet.

Over the weekend it also emerged Chancellor Philip Hammond and Environment Secretary Michael Gove clashed over the future of Britain’s fishing waters after Brexit.

It was reported that at a recent Cabinet meeting Hammond suggested using fishing rights in exchange for concessions on a future trade deal with the EU, a stance Gove is said to oppose.

“Philip and Michael had quite an exchange on what to do with fishing rights already,” a Cabinet source told The Sun.

“Michael was adamant that giving them away again would be a terrible betrayal of the coastal communities who all voted for Brexit.”

Earlier this month Gove told a conference in Denmark European fishermen would continue to have access to British waters after Brexit.

A spokesman for the Department of Environment, Food and Rural Affairs said after Brexit the UK would “grant fishing access for other countries on our terms”.