The European Union's chief Brexit negotiator has warned the UK will have to "face the consequences" if it chooses to leave without a deal.

In a BBC Panorama episode, Michel Barnier said that exiting prime minister Theresa May never told him the UK was willing to leave without a deal.

Mrs May has always publicly said that a no-deal is better than a bad deal, but Mr Barnier stressed that the prime minister "never" indicated it was an option or threatened it.

He said: "I think that the UK side, which is well informed and competent and knows the way we work on the EU side, knew from the very beginning that we've never been impressed by such a threat.

"It's not useful to use it."

When asked what would happen if the UK left on 31 October without a deal, Mr Barnier simply said: "The UK will have to face the consequences."

The programme also revealed claims that the EU offered to delay Brexit in 2018 by as much as five years and negotiate "a new deal for Europe". De facto deputy prime minister David Lidington said: "Martin [Selmayr, an aide to Jean-Claude Juncker] sort of said, 'Look, why don't we have a deal whereby we just put all this on ice for five years?'

"Let's see how things go, let's get the UK involved with France and Germany, let's see how the dust settles and let's talk about whether we can come to a new deal for Europe.'"

Former prime minister David Cameron attempted to renegotiate the UK's relationship with the EU prior to the referendum in 2016, but it was not deemed enough to satisfy the concerns of euro-sceptic MPs and politicians.

In his own interview, Mr Salmayr said he was "very certain" the UK wasn't ready to leave the EU without a deal.

He added: "We have seen what has been prepared on our side of the border for a hard Brexit. We don't see the same level of preparation on the other side of the border."

In another interview for the programme, the EU Commission's First Vice-President, Frans Timmermans, said it was "shocking" how under-prepared the UK's negotiating team was when the process began following the referendum vote.

He said the EU's team thought that "in some vault somewhere in Westminster there will be a Harry Potter-like book with all the tricks and all the things in it to do". Commenting on David Davis, who was the first Brexit secretary, Mr Timmermans, said: "I saw him not coming, not negotiating, grandstanding elsewhere [and] I thought, 'Oh my God, they haven't got a plan, they haven't got a plan.'

"That was really shocking, frankly, because the damage if you don't have a plan.

"Time's running out and you don't have a plan. It's like Lance Corporal Jones [from Dad's Army, you know, 'Don't panic, don't panic!' Running around like idiots."