Labour and the Liberal Democrats have called on Boris Johnson to sack the health secretary over his appointment of a close personal friend as an aide.
Questions about Matt Hancock hiring former lobbyist Gina Coladangelo have surfaced after pictures in The Sun newspaper appeared to show Mr Hancock, who is married, kissing the aide in his office.
Matt Hancock did not appear at a planned constituency event this morning.
An organiser at Newmarket Racecourse told Sky News earlier "he won't be coming". Asked when his appearance was cancelled they said: "Early this morning."
According to the newspaper, the images, which appear to be from CCTV footage, were taken on 6 May from the Department of Health and Social Care building.
The Sunday Times reported in November that Mr Hancock had failed to declare he had appointed Ms Coladangelo as an unpaid adviser on a six-month contract last March and later gave her a role on the board of the Department of Health.
Labour Party chair Anneliese Dodds said: "If Matt Hancock has been secretly having a relationship with an adviser in his office - who he personally appointed to a taxpayer-funded role - it is a blatant abuse of power and a clear conflict of interest.
"The charge sheet against Matt Hancock includes wasting taxpayers' money, leaving care homes exposed and now being accused of breaking his own Covid rules.
"His position is hopelessly untenable. Boris Johnson should sack him."
And Lib Dem leader Ed Davey said: "Matt Hancock is a terrible Health Secretary and should have been sacked a long time ago for his failures.
"This latest episode of hypocrisy will break the trust with the British public. He was telling families not to hug loved ones, while doing whatever he liked in the workplace.
"It's clear that he does not share the public's values. Rules for them and rules for us is no way to run a country.
"From the PPE scandal, the crisis in our care service and the unbelievably poor test and trace system, he has utterly failed. It is time for the Health Secretary to go."
Ms Coladangelo, who is listed on the department's website as a non-executive director, is the marketing and communications director at British retailer Oliver Bonas, which was founded by her husband Oliver Tress.
Her LinkedIn profile says she has been working as a non-executive director at the Department of Health since September 2020 and was at Oxford University at the same time as the health secretary.
Mr Hancock has been married to his wife Martha for 15 years and they have three children together.
Transport Secretary Grant Shapps said he would not comment on something that is an "entirely personal" matter.
But he added: "In terms of rules, anyone who's been appointed has to go through an incredibly rigorous process in government. Whatever the rules are, the rules will have to be followed."
Pressed again on whether the rules had been followed with regards to the appointment, Mr Shapps replied: "I think it's a bit of a red herring in this case. I think it's really a personal story, so I don't intend to comment on somebody's personal life."
He added that the health secretary "has been working very hard rolling out this vaccine programme".
A Department of Health and Social Care spokesman said: "This appointment was made in the usual way and followed correct procedure."
Peter Riddell, the Commissioner for Public Appointments, said last year that there were "growing concerns" about the lack of regulation over the appointment of non-executive board members to government departments.
He said that "the original idea of bringing in people with business and similar experience from outside Whitehall has been partly replaced by the appointment of political allies of ministers, in some cases without competition, and without any form of regulatory oversight".
The photo has also raised questions about whether Mr Hancock broke the government's lockdown laws.
At the time the picture was reportedly taken on 6 May, hugging anyone outside your household or bubble was not allowed.
The government's roadmap out of COVID restrictions said people should maintain their distance from anyone not in their household or support bubble until 17 May.
Human rights lawyer Adam Wagner, who has analysed COVID restrictions closely over the course of the pandemic, said on social media "there is an important question of whether the health secretary broke his own lockdown laws".
"Gatherings of 2 or more indoors were illegal except for permitted purposes… if they were at work, they might argue this fell within the work exception but I think - especially for health secretary - that's not a good argument".
"For the rest of the population, indoor relationships with someone you don't live with were (bizarrely) illegal until 17 May 2021."
Speaking to Sky News in May last year after it was revealed that Professor Neil Ferguson, who was then one of the government's top scientific advisers, had broken lockdown rules, Mr Hancock said he was "speechless".
Asked if he thought Prof Ferguson should have been prosecuted, the health secretary said: "It's a matter for the police, as a government minister I'm not allowed to get involved in the operational decisions of police matters.
"But I think the social distancing rules are very important and people should follow them."