Labour and SNP figures suggested Mr Sharp’s position was “untenable” after a cross cross-party committee found he failed to declare to MPs his role in facilitating the loan when he was applying for the job of BBC chairman.

They said his actions “constitute a breach of the standards expected of individuals” applying for prominent public appointments.

Speaking on Sunday morning, SNP MP John Nicolson, who sits on the Commons Digital, Culture, Media and Sport Committee, said Mr Sharp’s position is “extremely difficult”.

Richard Sharp's position is in increased peril after MPs found he made "significant errors of judgment" by acting as a go-between for a loan for Boris Johnson.

He told BBC’s Sunday With Laura Kuenssberg: “He has lost the trust of the BBC staff, that’s very clear, I’ve been deluged with messages from BBC staff saying they don’t see how he can head up the BBC any more.

“And he broke the rules: the rules are very clear, when you sign up for that job application you are asked if there’s anything about your relationships with anybody that could cause embarrassment.

“We knew he was a big Tory donor, we knew he had given hundreds of thousands to the Conservative Party, but what he didn’t tell us was that he had facilitated an £800,000 loan for Boris Johnson, the prime minister, who then gave him the job.

“It’s all a bit banana republic.”

Shadow Cabinet minister Lisa Nandy said his position at the BBC was untenable.

She told Sky News’ Sophy Ridge On Sunday the report by MPs was a “really serious development and it makes Richard Sharp’s position increasingly untenable”.

The shadow levelling up secretary said: “The Government has relied on the defence that the Culture, Media and Sport Select Committee approved this appointment, but the Culture, Media and Sport Committee today is saying that actually, had they known about this, it would have been a very different situation, this information was not disclosed to them prior to approving that appointment.

“Increasingly the circumstances around the relationship between the Conservative prime minister Boris Johnson and Richard Sharp is looking more and more murky and I think his position is becoming increasingly untenable as a result.”

Mr Sharp has insisted that he did not arrange the loan but admitted introducing his friend Sam Blyth, a cousin of Mr Johnson who wanted to help the then-prime minister with his financial troubles, to the Cabinet Office.

A spokesman for Mr Sharp said he “regrets” not telling MPs about his involvement with Mr Blyth “and apologises”.

Mr Sharp was named as the preferred candidate for the BBC job in January 2021 and the Commons Digital, Culture, Media and Sport Committee backed his appointment – but were not aware of his role in facilitating the £800,000 loan guarantee.

They have now suggested Mr Sharp’s failure to come clean could damage the BBC.

The report said: “Richard Sharp’s decisions, firstly to become involved in the facilitation of a loan to the then-prime minister while at the same time applying for a job that was in that same person’s gift, and then to fail to disclose this material relationship, were significant errors of judgment, which undermine confidence in the public appointments process and could deter qualified individuals from applying for such posts”.

Growing calls for BBC chairman to go after MPs find ‘significant errors of judgment’ over Boris Johnson loan