Muslim groups accused the British government of copying the language of the far right on Monday and of stoking Islamophobia after ministers wrote to imams asking them to explain to Muslims how Islam is compatible with being British.
In a letter to over 1,000 imams last Friday, Eric Pickles, the minister for local government and communities, asked them to explain to Muslims how Islam can be "part of British identity", arguing they had a duty to do more to fight extremism and root out anyone preaching hatred.
Muslim groups said the letter unfairly singled them out.
"The letter has all the hallmarks of very poor judgment which feeds into an Islamophobic narrative, which feeds into a narrative of us and them," Tahla Ahmad of the Muslim Council of Britain (MCB) told Sky News.
The row, which underscores tensions between the government and Muslims, comes as security forces warn that an attack on Britain by Islamist militants is highly likely. Jews and Muslims say they are fearful, for different reasons, after the Charlie Hebdo shootings in Paris.
Harun Khan, deputy secretary general of the MCB, said his organisation would be writing to the government to complain.
"Is Mr Pickles seriously suggesting, as do members of the far right, that Muslims and Islam are inherently apart from British society?" said Khan.
Mohammed Shafiq, chief executive of the Ramadhan Foundation, said the letter was patronising, factually incorrect, and "typical of the government only looking at Muslims through the prism of terrorism and security."
Britain's 2.8 million Muslims have been mostly praised by politicians for peacefully condemning the Paris shootings, though Sajid Javid, the most senior Muslim in government, has said Muslims have "a special burden" to track down extremists.
In the letter, Pickles said imams needed to help the government do something it couldn't achieve on its own: explain how Islamic faith can be part of British identity.
"We must show our young people, who may be targeted, that extremists have nothing to offer them ... show them these men of hate have no place in our mosques," the letter said.
Prime Minister David Cameron defended the letter as "the most reasonable, sensible" one Pickles could have written.
"Anyone frankly reading this letter who has a problem with it, I think really has a problem," he said.
Fiyaz Mughal, director of Tell Mama, an organisation that monitors anti-Muslim attacks, said it had registered a slight increase in incidents since the Paris killings, with death threats and hate mail sent to London mosques.
Police had also stepped up patrols at mosques in central England. "Muslim communities are feeling a sense of fear," he told Reuters.