Boris Johnson is under mounting pressure to hold an inquiry into claims a junior minister was sacked because of her “Muslimness” after a second Cabinet minister called for an investigation.

Health Secretary Sajid Javid followed Education Secretary Nadhim Zahawi in insisting that the incendiary allegations by Nusrat Ghani were properly looked into.

In an interview, Ms Ghani said that following her dismissal as a transport minister in February 2020, she was told by a Government whip that her faith made colleagues “uncomfortable” and that her career would be “destroyed” if she tried to complain.

In a fresh statement on Sunday, the MP for Wealden said she that after she spoke to Boris Johnson about what had happened, he wrote to her to say he “could not get involved”, and suggested she should use the internal Conservative Party complaints process.

“This, as I had already pointed out, was very clearly not appropriate for something that happened on Government business,” she said.

She added: “Now is not the time I would have chosen for this to come out and I have pursued every avenue and process I thought available to me, but many people have known what happened.

“All I have ever wanted was for his Government to take this seriously, investigate properly and ensure no other colleague has to endure this.”

Earlier, Deputy Prime Minister Dominic Raab said that there could be no inquiry unless Ms Ghani submitted a formal complaint which she had declined to do at the time.

Following the publication of her interview with the Sunday Times, the chief whip, Mark Spencer, confirmed he had spoken to her but strongly denied making the alleged comments saying the claims were “completely false” and “defamatory”.

However, she received powerful Cabinet backing from Mr Javid and Mr Zahawi, intensifying the pressure on the Prime Minister to act.

The Health Secretary tweeted: “This is a very serious matter which needs a proper investigation. I would strongly support her in making a formal complaint – she must be heard.”

Earlier, Mr Zahawi tweeted: “Nus Ghani is a friend, a colleague and a brilliant parliamentarian. This has to be investigated properly and racism rooted out.”

The row comes at a perilous moment for Mr Johnson as he awaits the publication of the report of Sue Gray into allegations of Downing Street parties in breach of lockdown rules, amid fears in No 10 it could trigger a new waves of demands for him to go.

The inquiry has also brought the conduct of the whips’ office under scrutiny amid claims it has sought to intimidate and blackmail Tory MPs trying to oust the Prime Minister over his conduct.

In her interview, Ms Ghani said said she was shocked to be told her “Muslimness’ was raised as an “issue” at a meeting in No 10 to discuss the February 2020 reshuffle, her “Muslim woman minister” status was making colleagues uncomfortable and that her loyalty was questioned because she “didn’t do enough to defend the party against Islamophobia allegations”.

“It was very clear to me that the whips and No 10 were holding me to a higher threshold of loyalty than others because of my background and faith,” she said.

“In the following weeks, I was informed that if I persisted in raising this that I would be ostracised by colleagues and my career and reputation would be destroyed.”

In a statement, a No 10 spokesman said Boris Johnson had met Ms Ghani after learning of her “extremely serious claims” in July 2020.

“He then wrote to her expressing his serious concern and inviting her to begin a formal complaint process. She did not subsequently do so,” the spokesman said.

In a further blow to the Prime Minister,tThe Sunday Times reported that Ms Gray has widened her inquiry to include allegations that parties were held in his Downing Street flat.

The paper said that two aides, Henry Newman and Josh Grimstone, both said to be friends of Mr Johnson’s wife Carrie, visited the flat over No 11 on numerous occasions during lockdown.

Initially, Ms Gray was said to have accepted the visits were for work purposes, however, investigators were reported to have questioned why they were spending so much time in Downing Street when they were working for the Cabinet Office.

Meanwhile, former Tory chief whip, Andrew Mitchell, has said it would be a criminal offence if claims that Government whips threatened to withdraw public funding from the constituencies of MPs who refused to toe the party line were true.

“There is an absolute rule that you do not go outside the stockade and use the media or blackmail to do in a colleague,” Mr Mitchell, the MP for Sutton Coldfield, told BBC Radio 4’s the World This Weekend.

“Using taxpayers’ money in a way to try and persuade a Member of Parliament not to vote in the way that they wish, that would be – if it were true, and I emphasise that is a quite a big ‘if’ – it would undoubtedly be misconduct in public office.

“It would be a criminal offence and it could result in a prison sentence.”

Tory MP William Wragg, the chairman of the Commons Public Administration and Constitutional Affairs Committee, who first raised the claims in Parliament is to meet police this week to discuss the allegations.