UK Prime Minister Theresa May has dismissed claims she is at loggerheads with European Commission President Jean-Claude Juncker over her Brexit negotiating strategy as just "Brussels gossip".

The Prime Minister came under fire following reports Mr Juncker walked out of talks last week in Downing Street saying he was "10 times more sceptical than before".

Opposition parties warned the UK was heading for a "disastrous hard Brexit" after a detailed account in the German press of their dinner suggested Mr Juncker left fearing the negotiations would end in failure.

But campaigning in Ormskirk in Lancashire, Mrs May brushed off the claims insisting that they were at odds with what the commission had said about the meeting.

"From what I have seen of this account, I think it is Brussels gossip," she said.

"Look at what the European Commission themselves said immediately after the dinner took place which was that the talks had been constructive."

Downing Street said it did not recognise the latest account which appeared in the German Frankfurter Allgemeine Sonntagszeitung newspaper.

The Prime Minister nevertheless sought to exploit the report to drive home her message that she - not Jeremy Corbyn - can provide the strong leadership needed to secure the best deal for Britain.

"It also shows that these negotiations are at times going to be tough and in order to get the best deal for Britain we need to ensure that we have got that strong and stable leadership into those negotiations," she said.

"When it comes June 8 people have a clear choice.

Mr Juncker reportedly left a meeting with Mrs May feeling Brexit talks could easily fail. Photo: Reuters

"There will be 27 European countries on one side of the table - who do they want to see standing up for Britain on the other side? Me or Jeremy Corbyn."

The Labour leader, campaigning in Battersea, south London, warned however that Mrs May's negotiating strategy was unravelling.

"To start negotiations by threatening to walk away with no deal and set up a low tax economy on the shores of Europe is not a very sensible way of approaching people with whom half of our trade is done at the present time," he said.

"Of course they are going to be difficult (negotiations), but you start from the basis that you want to reach an agreement, you start from the basis that you have quite a lot of shared interests and values.

"If you start from that basis and show respect, you are more likely to get a good deal.

"But if you start with a megaphone, calling people silly names, it is not a great start to anything."

According to the newspaper account - attributed to commission sources - the EU side left the meeting believing Mrs May was way too optimistic about the prospects for a deal.

When the Prime Minister told them "Let us make Brexit a success", Mr Juncker was said to have replied "Brexit cannot be a success".

At one stage - to underline the complexity of negotiations - the commission president was said to have brandished copies of Croatia's EU entry deal and Canada's free trade deal which runs to 2,000 pages.

Mrs May was also said to have angered the EU side when she warned that the UK could not be forced to pay a "divorce bill" for leaving because there was no requirement under the treaties, which drew the response that the EU was "not a golf club".

As he left, Mr Juncker was said to have told her: "I leave Downing St 10 times as sceptical as I was before."

The following morning he rang German chancellor Angela Merkel to warn her that Mrs May's approach was from a "different galaxy" and that she was deluding herself.

Mrs Merkel responded by re-writing a speech she was giving that day to warn that some in Britain were still harbouring "illusions" about the Brexit process.

No 10 said it did not recognise the account of the meeting which took place over dinner last Wednesday.

A Government spokesman said: "As the Prime Minister and Jean-Claude Juncker made clear, this was a constructive meeting ahead of the negotiations formally getting under way."

Liberal Democrat Leader Tim Farron said: "It's clear this Government has no clue and is taking the country towards a disastrous hard Brexit."

For the SNP, Scotland's minister for UK negotiations with the EU Michael Russell said: "Leaving the EU with no deal - and no agreement on access to the single market - would be an unprecedented act of self-harm which would devastate the UK and Scottish economy."

However, pro-Brexit Conservatives dismissed the report as an attempt to destabilise the Government ahead of the negotiations.

Former party leader Iain Duncan Smith told Channel 4 News: "The reality is there is no trouble because this is all pre-negotiation guff really, at the end of the day, so it should be put in that basket and then we'll get on with the negotiation."