BORIS Johnson is coming under increasing pressure to launch a formal investigation into claims that Matt Hancock “abused his position” as health secretary.

Both Labour and the SNP are demanding action after Hancock resigned in disgrace following the release of footage of him kissing aide Gina Coladangelo in his office.

Downing Street is being urged to explain why Coladangelo was appointed as an adviser and non-executive director at the Department of Health.

Questions have also been raised about Hancock’s use of private emails to conduct government business and claims that he concealed information from Whitehall officials and the public, including over multi-million pound coronavirus contracts.

Earlier, UK Justice Secretary Robert Buckland told Sky News he was confident “due process” was followed in appointing Coladangelo, but admitted he didn’t know when the romantic relationship began.

He commented: "If declarations weren't made then clearly that is highly irregular and inappropriate ... I don't know when the relationship began but I would expect that declarations should be made."

In response, SNP deputy Westminster leader Kirsten Oswald demanded an investigation.

"There are growing concerns that Matt Hancock routinely abused his position as Tory Health Secretary – and may have broken the ministerial code and the law on multiple occasions,” she said.

"It's essential that Boris Johnson orders an independent investigation to shine a light on Tory cronyism – or trust in the UK government will be eroded even further.

"The investigation must assess Mr Hancock's use of private email to conduct government business, his involvement in covid contracts that benefitted Tory friends and family, the appointment of Gina Coladangelo, and the repeated failure to declare relevant interests, including his relationship.”

The National: Questions remain over Gina Coladangelo's appointment at the UK Department of HealthQuestions remain over Gina Coladangelo's appointment at the UK Department of Health

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The SNP MP said Number 10 must not be allowed to “sweep the Tory cronyism under the carpet", adding that taxpayers’ must be given answers over why their money has been funneled into the pockets of Tory associates and donors.

She continued: “Whether it's soliciting dodgy donations to refurbish the Downing Street flat, handing peerages to billionaire Tory donors, offering tax breaks by text, or unlawfully handing covid contracts to Tory associates, there is a growing stench of corruption and sleaze about this Tory government.

"The Westminster system is rotten to the core and broken beyond repair. Instead of putting up with it, Scotland can shake off Westminster and build a fairer and more democratic future as an independent country."

Buckland told Sky News that an official inquiry is "a matter for the Cabinet Office”.

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According to The Sunday Times, leaked documents show the former health secretary may have hidden details of official dealings and his wider conduct in office.

In the minutes of a meeting between senior officials at the Department of Health and Social Care (DHSC) last December, the department's second permanent secretary, David Williams, said Hancock "only" deals with his private office "via Gmail account".

However, the Department for Health has claimed all ministers "only conduct Government business through their departmental email addresses".

Questions have also been raised about Hancock's involvement in helping his friend, and former landlord of his local pub, obtain a multi-million pound contract to supply test tubes for NHS Covid-19 testing.

When the former Tory minister was asked about the deal at a No 10 coronavirus press conference in December, he replied: "I had absolutely nothing to do with that contract."

But the Mail on Sunday, following a contested Freedom of Information request, obtained messages between Hancock and Alex Bourne in which he personally referred a plea for business to Jonathan Marron, the-then director general of community and social care at the Department of Health.

A message from Bourne, who runs a food packaging company, initially raised the possibility of making personal protective equipment such as surgical facemasks before later exchanges reveal a switch to producing items involved in coronavirus testing.

Bourne said his firm had signed a contract with an approved NHS distributor rather than directly with the Government and added: "This idea that I am chummy with [Hancock] is not true."

Labour deputy leader Angela Rayner said there must be “full transparency” and a “full investigation” amid claims Hancock used a private Gmail account.

She told the BBC Radio 4 Today programme: “I’ve written to ensure that there is an investigation into ministers using private emails to conduct official Government business in secret, agreeing contracts in private etc.”

She added: “We need full transparency on this and a full investigation.”

Buckland said ministers must use Government emails instead of Gmail, adding: “We should use Government emails, I think that’s very clear.

“I think the Cabinet Office, if they’re asked to look at this, they probably will be, will need to satisfy themselves that if that was the case then the material is available.”

There are also questions about how the footage of the kiss from CCTV inside a ministerial office emerged.

Tory MP Peter Bone has been granted an urgent question in the Commons about the security arrangements in ministerial offices, amid alarm that sensitive meetings and conversations may be monitored.

Buckland said he has been informed there is no CCTV in his office, telling Sky News: "I think there is an important principle here about the need for ministers and civil servants who often are handling very sensitive material and information to have a safe space within which to work.

"I'm sure that many of my colleagues will be asking the same question and be making sure the offices are swept just in case there are unauthorised devices that are in there that could be a national security breach."