Police are investigating after a fire destroyed a Somalian community centre and mosque in north London in what Scotland Yard said were suspicious circumstances.
The London Fire Brigade were called to the Somali Bravanese Welfare Association in Muswell Hill in the early hours and spent an hour tackling the blaze.
Both floors of the building were damaged and the structure had partially collapsed. One woman neighbour was treated for shock at the scene.
Police confirmed graffiti reading EDL (English Defence League) was found on the building and are investigating any potential connection between the graffiti and the fire.
Chief Supt Adrian Usher said: "I have spoken to community leaders and assured them that a thorough investigation is being conducted.
"The safety of our communities is always our priority and we are consulting widely, offering our support and reassurance. All communities can be confident that they have our support and I can be contacted personally to answer their concerns."
There have been no arrests at this stage.
There were fears that the mosque was firebombed in response to the killing of Drummer Lee Rigby in Woolwich two weeks ago.
Brother Abdool Ali, the president of Wightman Road Mosque in nearby Hornsey, said he was concerned by the fire in the wake of the Woolwich murder.
A London Ambulance Service spokesperson said: "Six fire engines and around 35 firefighters and officers were called to a fire at a community centre on Coppetts Road, Muswell Hill.
"The whole two-storey building was damaged."
The Mayor of London Boris Johnson described the alleged arson as a "cowardly, pathetic and utterly pointless" act.
He added: "There is no place in an open, tolerant and diverse city like London for hate, for prejudice, for violence.
"I would urge people to give the police the time and space to investigate this incident fully. I have no doubt the Met will bring those responsible to justice."
Andrew Dismore a London Assembly member for Barnet and Haringey, the area where the mosque is, said: "The fire is deeply saddening. We need to allow the authorities time and space to investigate this incident."
Since Rigby's death, there have been more than 200 reports of hate assaults on Muslims and attacks on mosques, according to Faith Matters, an organisation that works to reduce extremism.
The most serious was the attempted firebombing of the Grimsby Islamic Cultural Centre while worshippers were inside.
Anti-Islamic graffiti was sprayed on a mosque and a vehicle in Bolton, Greater Manchester, and there were reports of attacks on mosques in Gillingham and Essex.