In the comment piece, which argued against a blanket ban on burkas in the UK, Mr Johnson compared women who wore burkas to "letterboxes" and "bank robbers".
The party has received complaints that the comments breach its code of conduct, and under Conservative rules they must be investigated by an in- dependent panel. I would go further and say that it is absolutely ridiculous that people should choose to go around looking like letter boxes'. He is instead more likely to be told.
'You should really only apologise for a bad joke.
The founder of the Conservative Muslim Forum, Lord Sheikh, has written to Lewis demanding "serious action", while former attorney general Dominic Grieve said he would quit the party if Johnson became prime minister.
"Sir, As a lifelong beneficiary of the freedom to make jokes about religion, I do think that Boris Johnson's joke about wearers of the burka resembling letterboxes is a pretty good one".
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, victimize, harass or unlawfully discriminate against others". His Brexiteer credentials were bolstered when he resigned as foreign secretary in July, accusing May of killing "the Brexit dream" with her plan to seek close economic ties with the bloc after Brexit next year.
The party declined to comment on the disciplinary procedure.
"The burka and niqab are disgusting tribal ninja-like garments that are pre-Islamic, non-Koranic and therefore un-Muslim".
Defending Mr Johnson on BBC's Newsnight programme, Tory colleague and fellow MP Andrew Mitchell said: "We believe in free speech in this country; and free speech, by definition, includes the fact that some people will be offended by what we say".
He wrote: 'If you tell me that the burka is oppressive, then I am with you.
Boris Johnson's burqa comments have split the British population down the middle, with condemnation and support being handed out in equal measure.