Chancellor Sajid Javid said he has “full faith” in Boris Johnson as a storm over the Prime Minister’s private life risked overshadowing the Conservative Party conference.

Downing Street was forced to deny claims that Mr Johnson squeezed the thigh of a female journalist under the table during a private lunch.

The Conservatives will hope to get their party conference in Manchester back on track after a storm over the Prime Minister’s private life overshadowed the first day.

Charlotte Edwardes said the thigh-squeezing incident took place at the offices of The Spectator magazine in London shortly after Mr Johnson became editor in 1999.

READ MORE: Boris Johnson insists ‘no interest to declare’ over links with American businesswoman Jennifer Arcuri

After the lunch, she said she had confided in the young woman who was sitting on the other side of Mr Johnson, who told her: “Oh God, he did exactly the same to me.”

A Number 10 spokesman said: “This allegation is untrue.”

But Health Secretary Matt Hancock said he believed Ms Edwardes was trustworthy.

The Chancellor tried to evade questions about the row in a series of broadcast interviews.

“I don’t think it’s a good idea to get drawn into personal allegations,” he told the BBC.

“For my part, I’m not going to get into that.

“The Prime Minister has said that this is completely untrue. I have full faith in the Prime Minister, I don’t doubt what he has said for a second but I’m not going to get drawn into these allegations.”

Separately, the Prime Minister had to insist there was “no interest to declare” amid a storm over his association with the American businesswoman Jennifer Arcuri when he was mayor of London.

In a sign of Tory frustration that questions about Mr Johnson’s behaviour are taking attention away from policy announcements at the Conservative Party conference, Mr Javid acknowledged he would “rather be talking about the infrastructure revolution” he has promised.

Former Tory cabinet minister Justine Greening, who now sits as an independent, told BBC Radio 4’s Today programme: “I can’t comment on those accusations but they are deeply concerning and in a sense they go to the heart of this question about character and integrity of people in public life and what standards the electorate have a right to expect.”

Mr Javid is using the conference to set out plans for investments in roads, buses and broadband.

He will use a speech to the conference to outline the first projects that will be included in the promised road investment strategy, a £5 billion package to support the roll-out of broadband and a £220 million fund for buses.

Meanwhile, Housing Secretary Robert Jenrick will set out plans to cut red tape which could help homeowners looking to extend and small developers building new properties.

READ MORE: Call in Scotland Yard if Johnson fails to co-operate with 'conflict of interest' probes, says MP

And Work and Pensions Secretary Therese Coffey will announce that new apps aimed at helping young people find work are to be trialled as part of a multimillion-pound employment initiative.

The party will hope the announcements take attention away from the reports on Mr Johnson’s private life.

On Sunday, Health Secretary Matt Hancock, who said he knows Ms Edwardes well, said he believed her to be trustworthy, adding: “I entirely trust what she has to say.”

Asked if he believed her claims, he said: “I know her and I know her to be trustworthy.”

Former work and pensions secretary Amber Rudd has since said in a tweet “I agree with @MattHancock”.

Writing her first column for The Sunday Times, Ms Edwardes said: “I’m seated on Johnson’s right; on his left is a young woman I know.

READ MORE: Boris Johnson denies 'wandering hands' claim

“More wine is poured; more wine is drunk. Under the table I feel Johnson’s hand on my thigh. He gives it a squeeze.

“His hand is high up my leg and he has enough inner flesh beneath his fingers to make me sit suddenly upright.”

Labour’s shadow secretary for women and equalities Dawn Butler said it was a “shocking but sadly all too familiar story”.

“What is it about powerful men feeling entitled to harass women? Boris Johnson has serious questions to answer,” she tweeted.