THERE can be “no soft Brexit” for Britain, Michel Barnier has insisted, as he claimed the UK’s decision to leave the European Union was partly driven by “nostalgia”.

The EU’s chief Brexit negotiator, following this week’s inconclusive Brussels summit, warned that while 90 per cent of the deal was done, it could still fail over the Irish border issue.

Speaking to France-Inter radio, he said: "A deal is possible, it is desirable but it is difficult," noting how his hope was to complete it "in a few weeks or a few months; as soon as possible".

Mr Barnier admitted he had “no deep conviction” that an agreement could be reached, noting how the political situation in the UK was “very complex and I don't know what decisions Theresa May will take”.

He explained one "extremely serious" outstanding issue was the need to ensure there was no hard border in Ireland. Asked if the whole deal could fall over this one point, he replied bluntly: "My answer is yes."

While the chief negotiator acknowledged a failure to get a Brexit deal would be “very serious, very difficult for all of us in the EU,” it would be “much more grave for Britain".

Challenged over whether no-deal would mean dramatic disruption, such as flights being grounded, he said: "Emergency solutions would be found to establish a certain continuity but it would be extremely serious."

Mr Barnier then stressed the negative essence of Britain’s decision to leave the European bloc.

"There is no added value in Brexit. It is a negative negotiation. No-one has been able to show me any added value in Brexit, not even Mr Farage.

“When I met him in my office at his request and I asked him: 'Show me how the decision to leave the EU provides solutions to the anxieties, discontents and sometimes the anger of the British people.'"

He made clear he did not want to impose a hard Brexit on Britain, which he described as the “absence of a deal”.

"But Brexit can't be soft. It has innumerable consequences. It was chosen by the British. Were they well informed at the time they voted? They were not told all the consequences; even Mr Farage recognised that everything was not spelt out in the campaign."

Mr Barnier said he believed that the Brexit vote was driven in part by "nostalgia" as well as the UK's desire to extricate itself from regulations, particularly in the financial sector, and popular anger over the impact of economic liberalisation.

But David Davis, the former Brexit Secretary hit back, saying: "I wouldn't confuse belief in the free market with nostalgia.”

Earlier, Jeremy Hunt rejected claims that Theresa May had "capitulated" in the face of EU demands.

The Foreign Secretary insisted: "The reason why this week has been difficult is because Theresa May has not buckled. She has held firm. She has stuck to her principles. It is precisely because she has not capitulated that we have not concluded this agreement.”

After attending the EU-Asia summit in Brussels, the Prime Minister briefed around 130 business leaders on the Brexit negotiations, hosting a video roundtable with chief executives and chairmen and women from firms including Tesco, RBS and Diageo, plus business groups like the CBI and Federation of Small Businesses.

Meanwhile, Sammy Wilson, the Democratic Unionists’ Brexit spokesman, took Leo Varadkar, the Irish premier, to task after he warned that violence could again return to the island of Ireland if a hard border was imposed post-Brexit.

Branding the Taoiseach “vile,” Mr Wilson accused him of "despicable, low and rotten" behaviour, claiming Mr Varadkar was scraping the bottom of a "very deep barrel of threats, deception and rhetoric".

But Simon Coveney, Ireland’s Deputy Prime Minister, defended his colleague, saying: "We are not trying to scaremonger here, what we are trying to do here is protect a very precious peace and normality on the island of Ireland."