Speaking to reporters on Monday, the prime minister's official spokesman said Mr Johnson was "not aware of any specific allegations being looked at" and "in the absence of formal complaint, it was not deemed appropriate to stop an appointment on the basis of unsubstantiated allegations".

But he said the PM was "aware of media reports that others had seen over the years and some allegations that were either resolved or did not progress to a formal complaint", so sought advice from his propriety and ethics team before his appointment.

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Mr Pincher quit the role last week after he was accused of drunkenly groping two men at a private members' club in London on Wednesday.

The Tory whip was only removed from him on Friday afternoon - meaning he now sits as an independent MP.

It was the second time the MP for Tamworth in Staffordshire resigned from the whips office, after Conservative candidate Alex Story accused him of making an inappropriate advance in 2017.

But questions have been raised about what the prime minister knew before appointing Mr Pincher in February, with allegations by former chief of staff Dominic Cummings that Mr Johnson referred to the MP as "Pincher by name, pincher by nature" beforehand.

Labour Party chair Anneliese Dodds has written to the PM demanding answers, claiming Mr Johnson is "clearly happy to sweep sexual misconduct under the carpet in order to save his own skin".

Speaking to Sky News' Kay Burley earlier, education minister Will Quince said he has been given "categorical assurance" from Number 10 that Boris Johnson was "not aware of any serious specific allegations" against Mr Pincher, when he was appointed.

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'Impossible to believe' PM not aware of any claims

But Labour's Jenny Chapman said she found it "impossible to believe" the PM was unaware of any claims, as there were "widespread rumours" about Mr Pincher's behaviour in Westminster.

"These things were well known," she told Kay Burley. "What kind of person decides what we need to do with this guy [is] to give him a really big promotion?

"That's what Boris Johnson did. And he did it because it's his mate, and we think that's wrong."

Education Secretary Nadhim Zahawi said the prime minister had "acted decisively" over removing the whip from Mr Pincher, but said due process needed to be followed in any investigation.

Asked why he believed Mr Pincher was appointed to the post in the first place, he added: "The values of this country are about innocence until proven guilty."

The Number 10 spokesman said he "did not intend to respond" to the "unsubstantiated" claims by Mr Cummings.

But asked whether the PM was concerned about the alleged behaviour of Mr Pincher, the spokesman said: "We wouldn't want any anyone working with the government to behave in the manner in which he is alleged to have done so… it is not the behaviour that you'd want to see in any walk of life."

Mr Quince also said the allegations against Mr Pincher were "shocking and appalling", and that they did "huge damage to the reputation and trust in parliament".

He also said it was important to "call out" such behaviour, urging other people affected to come forward and, "if the allegation is serious, of course I would encourage people to go to the police".

Mr Pincher is now under investigation by parliament's Independent Complaints and Grievances Scheme.

He said he is seeking "professional medical support" and hopes to return to represent his constituents "as soon as possible".