Hooded youths in Hackney pushed burning rubbish bins down a street towards police on Monday, laughing as they ran back when police charged them. Others smashed their way into a shop and ran off clutching bottles of whisky and beer.

Reuters witnesses saw similar scenes in Woolwich, Clapham in the south and Ealing in the west. In Ealing, one resident told Reuters about 150 hooded youths had walked down his road smashing car windows in a display of "mindless vandalism".

"It's very sad to see ... But kids have got no work, no future and the cuts have made it worse. These kids are from another generation to us and they just don't care," said Hackney electrician Anthony Burns, 39.

"You watch. It's only just begun."

Government officials branded the rioters criminals and said the violence would have no effect on prepI likarations for the 2012 London Olympic Games - though television images of blazing buildings and rioting were likely to dent the capital's image.  

"It was needless, opportunistic theft and violence, nothing more, nothing less. It is completely unacceptable," said Deputy Prime Minister Nick Clegg.

Cameron has resisted calls to slow the rate at which he is cutting the budget deficit in order to lessen the impact on youth services and other facilities. He was likely to come under new pressure to do more for poor districts of the capital.

The first riots broke out on Saturday in London's northern Tottenham district, when a peaceful protest over the police shooting of a suspect two days earlier was followed by outbreaks of looting.

Further disturbances followed on Sunday, and on Monday, emboldened by the inability of the police to concentrate their forces in every trouble spot, looting spread rapidly.