Nusrat Ghani, 50, said last year that she had been told by a whip - an enforcer of parliamentary discipline - that her Muslim faith was making colleagues uncomfortable and was a factor in her sacking as junior transport minister in February 2020.

Then Prime Minister Boris Johnson ordered an inquiry into the allegations in January 2022.

Announcing the inquiry's findings, Laurie Magnus, Sunak's independent adviser on ministers' interests, said Ghani's concerns were "very serious", but that he was unable to determine what exactly transpired in meetings between her and the government's then chief whip Mark Spencer.

He said he had received conflicting evidence from each of them and that there was no evidence to suggest that negative comments about Ghani's faith were made, but also that it was not possible to conclude they were not.

"In the absence of clear evidence, it would not be right to take further action," Sunak wrote in a reply to Magnus.

The Conservative Party has previously faced accusations of Islamophobia, and a report in 2021 criticised it over how it dealt with complaints of discrimination against Muslims.

Ghani said Magnus's report showed her evidence had been consistent, and there was no criticism expressed about her version of the events.

"We all serve at the Prime Minister's choosing and there is no shame in a political career ending," Ghani said in response to the report. "But to be told your faith and identity is the reason for it cannot be acceptable in any way."

Spencer did not immediately respond to a request for comment. Both he and Ghani are currently ministers in Sunak's government.