Prime Minister Boris Johnson has ordered a Cabinet Office inquiry into claims made by a Muslim MP who says her faith was given as a reason for her sacking as a minister in 2020.
Nusrat Ghani said a government whip told her “Muslimness was raised as an issue”.
The Conservative MP welcomed the inquiry, saying all she wanted was for the matter to be taken seriously.
Conservative Chief Whip Mark Spencer said the claims were completely false.
He said Ms Ghani was referring to him and that he considered her allegations to be defamatory.
The new Cabinet Office inquiry comes at the beginning of what could be a difficult week for the prime minister, with the expected completion of a report into gatherings on government premises that took place when coronavirus restrictions were in place.
Senior civil servant Sue Gray has been asked to look at the nature and purpose of the gatherings, including who went to them “with reference to adherence to the guidance in place at the time”.
Mr Johnson has faced calls from some of his MPs to resign over the matter, but others say they are withholding judgement until the findings of Ms Gray’s report are published.
Responding to news of the inquiry, Ms Ghani 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 of the inquiry must include all that was said in Downing Street and by the whip.”
She said she was also told that her “Muslim woman minister status was making colleagues feel uncomfortable” and that there were concerns “that I wasn’t loyal to the party as I didn’t do enough to defend the party against Islamophobia allegations”.
He added: “I consider them to be defamatory. I have never used those words attributed to me.”
Ms Ghani has also claimed that when she raised the matter directly with the PM, he told her he could not get involved.
A No 10 spokesperson said: “At the time these allegations were first made, the prime minister recommended to her that she make a formal complaint 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.”
Speaking on Sunday, Ms Ghani said when she had not used the Conservative Party’s internal process because it was “very clearly not appropriate for something that happened on government business”.
Baroness Warsi, the first Muslim woman to attend Cabinet, said Ms Ghani’s experience had been “an open secret in Westminster” and that she had “struggled to be heard” for nearly two years.
The former party chair said that she believed there was a “pattern” with Islamophobia in the Conservative party, where “Islamophobic racism is not viewed as seriously as other forms of racism” and “action is rarely taken until the media is involved”.
She called for the Equalities and Human Rights Commission (EHRC) to intervene arguing the government might have broken the law.