Boris Johnson is to face investigation by an independent panel following complaints that his comments comparing women who wear the burka to "bank robbers" and "letter-boxes" breached the Conservative Party’s code of conduct.
It is understood that the process is being triggered automatically after the receipt of a number of complaints over the former foreign secretary’s comments in a column for the Daily Telegraph in which he also defended women's choice to wear the veil.
The Tory party declined to comment on the disciplinary procedure.
On the same day that the investigation was launched, a letter signed by around 100 Muslim women who wear the burka or niqab has also been sent to Conservative Party chairman Brandon Lewis backing calls for action against Mr Johnson as well as supporters such as Conservative MP Nadine Dorries.
The letter reportedly states: "Given a deliberate choice was made to inflame tensions in a way which makes it easier for bigots to justify hate crimes against us, we concur with the Conservative peer Lord Sheikh who has demanded that the whip be withdrawn from Mr Johnson.
"Furthermore, given the responses from other MPs, specifically Ms Dorries, and the broader concerns raised by the Muslim Council of Britain amongst others, we believe there must now be an independent inquiry into Islamophobia in the party to tackle this issue once and for all."
Sidrah Sajad, a signatory of the letter, said she had added her name to it as she felt "the need to be heard", adding that it was "important for Muslim women who wear the veil to come forward and express how they feel about Boris Johnson's remarks".
She continued: "We want everyone to know that we are citizens of the United Kingdom, and we as British citizens want to feel valued and respected in our beliefs, that we wear what we wear for choice.
"There's a misconception of people thinking that we're oppressed and forced to wear this, but it's our personal choice... whatever the reason a woman wears what she wants, no one should question her on that."
Ms Sajad continued that people who do not wear the niqab or burka "don't need to understand why we wear it, you just need to accept it... and respect it...
"I don't question people who wear shorts, bikinis, have tattoos... whatever personal preference they have, I don't question that, I never judge a person by their cover.
"Don't judge a book by it's cover, don't judge a Muslim woman who wears a veil, by her veil."
Mr Johnson soon came under criticism from within his own party for making the comments, with Mr Lewis and the Prime Minister ordering him to apologise.
Mr Johnson has not yet issued an apology or retracted his remarks.
On the back of his comments, some Muslim leaders and MPs have called for an inquiry into Islamophobia in the Tory party.
Assistant Secretary General of the Muslim Council of Britain Miqdaad Versi said the current controversy was just part of "weekly occurrences of Islamophobia by members of the Conservative party."
He added: "What is happening when you have a party where this number of incidents continues to occur and no action is being taken?"
There have been accusations that the remarks he made are racist, but Scotland Yard chief Cressida Dick said that while many have found the remarks offensive, officers have found he did not commit an offence.
Tory party rules make clear that formal complaints against Conservative representatives will be investigated “in a timely and confidential manner” by someone “with appropriate experience and no prior involvement in the complaint”.
“The investigation should be thorough, impartial and objective, and carried out with sensitivity and due respect for the rights of all parties concerned."
However, the party would not offer comment on Mr Johnson's case, saying "the code of conduct process is strictly confidential".