Boris Johnson is facing a possible investigation into breaches of the Conservative Party code of conduct.
The party has received dozens of complaints about the former foreign secretary’s comments about women wearing burkas, who he said looked like letter boxes.
The complaints will be looked at by an independent panel.
A Conservative Party spokesman said: “The code of conduct process is strictly confidential.”
Mr Johnson has rejected calls to apologise for his remarks, in a Daily Telegraph column in which he also argued against a ban on full-face veils.
Critics have accused him of stoking Islamophobia to boost his Tory leadership ambitions but his supporters have said he was speaking up for “liberal values”.
The Conservative Party has also been accused of not doing enough to tackle anti-Muslim prejudice in its ranks, despite an initiative to boost tolerance and diversity.
The party’s code of conduct states that Tory officials and elected representatives must “lead by example to encourage and foster respect and tolerance” and not “use their position to bully, abuse, victimise, harass or unlawfully discriminate against others”.
The independent panel will decide whether to refer Mr Johnson to the party’s board. Possible action includes suspension of membership or expulsion from the party among other things.
Conservative Party chairman Brandon Lewis and leader Theresa May have both called on Mr Johnson to apologise for his comments.
Boris Johnson facing possible Tory probe over burka comments}