The murder of soldier Lee Rigby has prompted a huge increase in reported attacks against Muslims, an anti-extremist organisation has said.
Faith Matters said four to eight cases a day were reported to its helpline before Wednesday's brutal killing.
But about 150 incidents had been reported in the last few days, including attacks on mosques, the group said.
It came as police forces across the country continued to make arrests over allegations of racist comments on social media sites.
Fiyaz Mughal, director of Faith Matters, told BBC Radio Five Live: "What's really concerning is the spread of these incidents. They're coming in from right across the country.
"Secondly, some of them are quite aggressive, very focused, very aggressive attacks. And thirdly, there also seems to be significant online activity...suggesting co-ordination of incidents and attacks against institutions or places where Muslims congregate."
Several people have been arrested and appeared in court in connection with remarks made following the killing of Drummer Rigby, 25, who was brutally hacked to death in Woolwich, south east London.
Yvette Cooper, the shadow home secretary, said: "Anyone who seeks to divide our communities is doing the work of the extremists they say they oppose. Mindless acts of violence against any of our communities serve no one. Some people are trying to use the vile attack in Woolwich as an excuse for more hatred, violence, and extremism. We must not let them.
"The police, security services and all right minded people in this country will do everything they can to make sure any act of violence and intimidation is dealt with robustly and quickly.
"The clear message from the overwhelming majority of British people is - 'not in my name'. We stand together against violent extremism, intolerance and hatred - whether it comes from Islamist extremists, the EDL, the BNP, or extremists of any kind."