Muslim leaders are bracing themselves for more acts of "revenge" after those who committed the terrorist attacks in London were revealed to have been suicide bombers.
Mosques were targeted in racist incidents over the weekend, including two fire-bombings on Islamic buildings in Leeds and Bradford.
Dr Ghayasuddin Siddiqui, leader of the British Muslim Parliament, said he was concerned that some people would be led to believe that all Muslims were capable of suicide bombings. "It is something that the Muslim community feared the most - that these people implicated in the attack may have been home-grown," he said. "People will start to draw the wrong conclusion and say that perhaps every Muslim is like them."
He said that Thursday's attacks were made by a group of "lunatics" who happened to be living in Muslim communities. "There are lunatics in all societies and this attack was against all human values. We must show restraint and stand together because as far as ordinary Muslims are concerned we are all together in this fight."
Police in Yorkshire were quick to reassure the Muslim community after anti-terrorist officers raided a number of addresses in Leeds.
Colin Cramphorn, Chief Constable of West Yorkshire, said that he was aware that racists might seek to exploit public concerns about the threat from terrorism.
But he said: "I urge the public to continue to be alert but not alarmed by events here today. I also urge them to reject any form of extreme response to them.
"Finally, I ask that people continue to be calm, resilient and measured in what they say and how they act. We cannot afford to let those who seek to undermine our society succeed. West Yorkshire Police is here to protect and serve all the communities of West Yorkshire."
A mosque in the constituency of the Home Secretary, Charles Clarke, has become the seventh Islamic building to be targeted in the wake of the bombings.Mr Clarke, MP for Norwich South, said: "In general I believe there has been a united opposition to the terrorist attacks and people from all faiths have responded in a very positive way."
A spokeswoman for Norfolk Police said that two women, aged 23 and 26, were arrested near the Islamic Centre in Rose Lane, Norwich, on Sunday at about 3am.
Ustar Ali, chairman of the Norwich mosque's committee, said: "It's hard to pinpoint exactly what happened on Sunday morning. I am quite easy about it and don't want to make it into a big issue. At the end of the day it's nothing compared to what happened in London. What happened there was carried out by sick, brainwashed people."
The Metropolitan Police promised to crack down on anyone involved in racist "revenge" attacks. Deputy Assistant Commissioner Brian Paddick said there had been several attacks on Asians in the capital since the bombings.
He said: "We need people from every community to report incidents to the police of any faith-hate crime and any other hate crime. Police will deal with these offences robustly. We will not tolerate a small minority of people who are using these tragic events to stir up hatred.
"Londoners are not attacking each other. They are being united by this terrible tragedy and we need to make sure we all stick together."