Prime Minister Boris Johnson has asked the Cabinet Office to conduct an inquiry into allegations made by Conservative MP Nusrat Ghani.
Ms Ghani claimed she had been sacked as a junior minister because of concerns about her “Muslimness”.
Over the weekend two cabinet ministers – Health Secretary Sajid Javid and Education Secretary Nadhim Zahawi – backed calls by Nusrat Ghani for an inquiry into her treatment.
And on Monday morning, Mr Johnson asked for an inquiry into her claims.
A No 10 spokeswoman said: “The Prime Minister has asked the Cabinet Office to conduct an inquiry into the allegations made by Nusrat Ghani MP.
“At the time these allegations were first made, the Prime Minister recommended to her that she make a formal complain to CCHQ (Conservative Campaign Headquarters).
“She did not take up this offer.
“The Prime Minister has now asked officials to establish the facts about what happened.
“As he said at the time, the Prime Minister takes these claims very seriously.”
Education Secretary Nadhim Zahawi said on Monday (January 24) there will be an investigation into the claims.
The Cabinet minister told Sky News: “She has made a very serious allegation, the Prime Minister spoke to her last night and said the Cabinet Office will investigate this and look at the detail of this.
“She put out a statement last night saying actually, to be fair to her, this could be people who weren’t even members of the Conservative Party, which is why we need to get to the bottom of this very quickly."
Boris Johnson had been 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 Mr 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.”
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 an 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.