The Muslim Council of Britain has taken the unprecedented step of writing to every British mosque, urging people to help in the fight against terror.
The letter asks for the "utmost vigilance" to help "safeguard" the UK.
Prime Minister Tony Blair welcomed the move saying it made clear that terrorism "has nothing to do with the true message of Islam".
It comes as police continue to question eight men arrested in raids across the south-east of England.
Half a ton of ammonium nitrate fertiliser - a bomb-making ingredient - was also seized from a London warehouse during the same anti-terror operation on Tuesday.
Mr Blair, speaking in the House of Commons, thanked Britain's police and security services for their work.
"As we have said, the UK and its interests abroad remain a terrorist target and the government and the services will continue to do all we can to fight terrorism in every way."
He said the threat "affects every family in this country, Muslim and non-Muslim alike, and it is right that we all work together to defeat this threat and do not allow the extremists to divide us".
Foreign Secretary Jack Straw said the government must improve its relations with British Muslims.
In a video message to the annual Muslim News awards, Mr Straw said: "It is more important than ever before that we in government build a close relationship and dialogue with Muslim communities.
"We must learn to emphasise both the richness of our shared history and the outstanding contribution which Muslims make to all walks of life in Britain today."
'Muslim backlash'
Muslim Council Spokesman Inayat Bunglawala said the decision to send the letter was made following the Madrid rail bombings of 11 March which left 191 dead. It was then redrafted to take Tuesday's arrests into account.
It calls on Muslims to report any suspicious activity to the authorities.
"Islam categorically forbids violence and killing of innocents, let alone indulging in violence which can cause death and mayhem," it states.
Mr Bunglawala told BBC News Online: "It's also a message urging Muslims not to get downhearted - they're under massive pressure. They must be worried about recent events.
"We're seeing a backlash against Muslims but Muslims must not lose heart."
Sermons will be delivered on Friday saying terrorism has no place in Islam, while booklets being printed will remind Muslims of their obligation to help safeguard Britain's security.
"A terrorist attack will not discriminate between Muslims and Christians", Mr Bunglawala said.
"As British citizens, we have a right to help the safeguarding of this country by co-operating with police."
However he also urged caution because a number of "high-profile arrests in the past of Muslims" had led to no charges or convictions.
His comments were echoed by Ahmed Versi, editor of the Muslim News, who warned that British Muslims felt "under siege".
'Islamophobia'
More than 700 officers from five forces carried out raids on 24 premises early on Tuesday morning.
The police have to be very sensitive and ensure that they have the evidence otherwise it will be counter-productive