Chief EU negotiator Michel Barnier warns Theresa May Brexit talks will be a 'steep and rocky path'

Chief EU negotiator Michel Barnier has warned Theresa May that Brexit talks will be a “steep and rocky path” with perilous dangers ahead.

As he unveiled his negotiating mandate, Mr Barnier compared pending negotiations to mountain walking, fraught with hazards like “falling rocks” and argued that Brexit would not be “painless”.

Mr Barnier said he discussed his interest in mountain walking with Ms May, who loves rambling, during the Downing Street meeting which is at the heart of a controversial leak scandal.

Details of the face-to-face also attended by Jean Claude Juncker, were later passed to a German newspaper which suggested the European Commission President believed Ms May’s to be “deluded” over Brexit.

Saying that he found the No10 meeting “cordial”, Mr Barnier went on: “On a personal basis I had the opportunity to discuss a shared passion with Theresa May which is rambling and hiking in the mountains.”

He added: “If you like walking in the mountains you have to learn a number of rules. You have to learn to put one foot in front of the other, because sometimes you are on a steep and rocky path.

“You also have to look what accidents might befall you – falling rocks. You have to be very careful to keep your breath, you have to have stamina, because it could be a lengthy path and you have to keep looking at the summit.”

Mr Barnier said he wanted to build an “entente cordial” that will last well beyond Brexit, but he attacked those – without naming names – who had suggested there would be no consequences to the UK’s withdrawal.

He also hit out at the idea, promoted by Theresa May, that a full agreement could be reached in the Article 50 period and that negotiations on withdrawal and a future trade deal could take place at the same time.

Mr Barnier said: “Some have created the illusion that Brexit will have no material impact on our lives and that it will be painless. This is not the case.”

He went on: “Those who pretend, or who did pretend that you can leave the European Union and there will be no consequences simply aren’t telling the truth.

“There are human consequences, there are social consequences, there are economic consequences, there are technical consequences, financial and legal consequences.

“You are unwinding 43 years or so of a relationship. That’s why you can’t do everything in 15 or 16 months. That’s why things have to be done in a given order. At some stage you build an idea of a future relationship.”

Mr Barnier said the people he had spoken to in London appeared to be aware of the difficulties that lay ahead.

At a press conference in London, Brexit Secretary David Davis said the British public wanted the best possible outcome from the talks, adding: "We do that in the negotiating room, not by negotiating with a megaphone."

He acknowledged there would be "tough times" during the process "when you come under pressure, and this is one of those times".

Mr Davis said he did not recognise the numbers being "bandied around" for the Brexit fee, which now reach up to €100bn, and he insisted Ms May would play a full part in the negotiations, following claims that she would not be able to take a frontline position.

"We will decide the structure of our negotiating team, not the EU," he added.

Chancellor Philip Hammond said: "What this episode shows is just how tough the negotiation is going to be. The question people have got to ask themselves as they go into the polling booth on June 8 is who do they want conducting these negotiations for Britain? Theresa May or Jeremy Corbyn? Who is most likely to get the deal that's right for Britain?"

He said the potential Brexit fee was "just a negotiating position" and "we are on the brink of a very tough, complex, lengthy negotiation and I'm not remotely surprised that people are manoeuvring for opening advantage in that negotiation".