Boris Johnson has come out against calls to ban face-covering garments like the burka in public places.
The former foreign secretary said Denmark was wrong to impose fines for wearing the burka or niqab in the streets.
But he came under attack for saying that Muslim women in burkas “look like letter boxes”, and comparing them to bank robbers and rebellious teenagers.
Labour MP David Lammy branded Mr Johnson a “pound-shop Donald Trump” and accused him of “fanning the flames of Islamophobia” for political advantage.
Denmark last week followed France, Germany, Austria and Belgium in banning the burka in public places.
A fine of around £120 has already been imposed on a woman wearing one in a shopping centre in the town of Horsholm, after another woman reportedly tried to tear it off.
Writing in the Daily Telegraph, Mr Johnson said he felt “fully entitled” to expect women to remove face coverings when talking to him at his MP’s surgery, and said schools and universities should be able to take the same approach if a student “turns up … looking like a bank robber”.
“If you tell me that the burka is oppressive, then I am with you,” he wrote.
“If you say that it is weird and bullying to expect women to cover their faces, then I totally agree – and I would add that I can find no scriptural authority for the practice in the Koran.
“I would go further and say that it is absolutely ridiculous that people should choose to go around looking like letter boxes; and I thoroughly dislike any attempt by any – invariably male – government to encourage such demonstrations of ‘modesty’.”
Businesses and government agencies should also be able to “enforce a dress code that enables their employees to interact with customers”, including by allowing them to see their faces, said Mr Johnson.
But he added: “Such restrictions are not quite the same as telling a free-born adult woman what she may or may not wear, in a public place, when she is simply minding her own business.
“I am against a total ban because it is inevitably construed – rightly or wrongly – as being intended to make some point about Islam.”
A total ban would give a boost to radicals who claim there is a “clash of civilisations” between Islam and the West, fanning the flames of grievance and turning women into “martyrs”, he warned.
And he said that a ban on burkas could lead to “a general crackdown on any public symbols of religious affiliation”.
Mr Johnson wrote: “Like a parent confronted by a rebellious teenager determined to wear a spike through her tongue, or a bolt through her nose, you run the risk that, by your heavy-handed attempt to ban what you see as a bizarre and unattractive adornment, you simply stiffen resistance…
“If Danish women really want to cover their faces, then it seems a bit extreme – all the caveats above understood – to stop them under all circumstances. I don’t propose we follow suit. A total ban is not the answer.”
Mr Lammy responded on Twitter: “Muslim women are having their burkas pulled off by thugs in our streets and Boris Johnson’s response is to mock them for ‘looking like letter boxes’.
“Our pound-shop Donald Trump is fanning the flames of Islamophobia to propel his grubby electoral ambitions.”