Boris Johnson has ordered an inquiry into Tory Nusrat Ghani's claim that she was told she had been fired from a Government job due to her Muslim faith.
The former Transport Minister said she considered quitting politics after a whip allegedly told her that her "Muslimness was raised as an issue" at a meeting in Downing Street and that her “Muslim woman minister status was making colleagues feel uncomfortable”.
Ms Ghani was sacked from her role as a Transport Minister in a reshuffle in February 2020.
Chief Whip Mark Spencer identified himself as the person at the centre of the claims on Saturday - but insisted they were "completely false".
Today, the Prime Minister said he was taking the allegations "extremely seriously" and an investigation would take place.
Speaking on a visit to a hospital in Milton Keynes, he said: "We take these allegations extremely seriously, I took them very seriously when they were raised with me 18 months ago... very glad there's an investigation taking place now.
"I can't say more, really, about it."
Asked if Chief Whip Mark Spencer could stay in post while the investigation was conducted, Mr Johnson dodged the question, saying: "This is something I take personally extremely seriously, I took it very seriously 18 months ago, we must wait and see what the investigation produces."
Downing Street confirmed on Monday that the Cabinet Office would conduct an inquiry into Ms Ghani's allegations.
A No10 spokesperson 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. 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.”
The PM spoke to Ms Ghani last night to inform her of the decision.
Ms Ghani welcomed the inquiry but warned it needed to include everything said in Downing Street and by the whip.
In a statement on Monday, she said: "As I said to the Prime Minister last night, all I want is for this to be taken seriously and for him to investigate.
"I welcome his decision to do that now. The terms of reference for the inquiry must include all that was said in Downing Street and by the whip.
"I look forward to seeing the terms of reference."
Ms Ghani's allegations sparked outrage over the weekend, with a string of senior Tories speaking out in support.
Both Education Secretary Nadhim Zahawi and Health Secretary Sajid Javid spoke publicly over the need for an inquiry into her claims.
Ms Ghani told The Sunday Times that she was told by a Government whip that her faith made colleagues "uncomfortable" after her dismissal as a junior minister in February 2020.
She said she was told that her career would be "destroyed" if she tried to complain.
The Chief Whip, who identified himself as the subject of her claim, said in a statement: "These accusations are completely false and I consider them to be defamatory.
"I have never used those words attributed to me."
Ms Ghani declined to make an official complaint at the time.
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."
It comes at the start of a nightmare week for Boris Johnson as he awaits to findings of Sue Gray's report into the Downing Street saga, which could determine his political future.