LONDON - Britain's biggest Muslim association on Monday accused the government of stoking Islamophobia and making a far-right argument over a letter urging community leaders to do more to root out extremism.

But Prime Minister David Cameron defended the letter saying it was "reasonable, sensible and moderate". "Anyone... reading this letter, who has a problem with it, I think really has a problem," he said.

The controversy surfaced as security was stepped up for British police, who were told to withhold their home addresses from electoral lists, two weeks after attacks in Paris in which 17 people including three police officers were killed.

The letter sent to mosques praised British Muslims for rejecting the attacks but said imams must do more to prevent radicalisation in their own communities.

"You have a precious opportunity, and an important responsibility: in explaining and demonstrating how faith in Islam can be part of British identity," said the letter from Communities Secretary Eric Pickles.

"There is a need to lay out more clearly than ever before what being a British Muslim means today: proud of your faith and proud of your country," it added.

The Muslim Council of Britain condemned the letter. "Is Mr Pickles seriously suggesting, as do members of the far-right, that Muslims and Islam are inherently apart from British society?" the council's deputy secretary-general Harun Khan said. The MCB's Talha Ahmad told Sky News: "The letter has all the hallmarks of very poor judgement which feeds into an Islamophobic narrative".

Police in Britain meanwhile said they had given security advice to officers, bolstered security around police buildings and increased "levels of specialist support, including firearms officers".

"Our experience of policing London and the UK tells us that our key focus should be on how to prevent attacks," a police statement said.

"The best way to do this is to engage even more widely with our communities to encourage them to pass on information," it said.