Peter Hunt reports: "Millions of pounds worth of damage has been inflicted"

Jack Straw said that although information on the protest was available on the Internet, police attempts to contact the organisers were rejected.

He said some of the demonstrators were "intent on violence" from the start.

The home secretary refused to speculate on media reports of orchestrated violence.

The protest was linked to the G8 summit, which tried to tackle Third World debt

"I have no information about whether some of the rioters were provided with packed lunches or paid to attend, but that may be a matter for the police investigation."

But he said the refusal to share information with police made clear the organisers' intention to create maximum disturbance.

"This country has a fine tradition of peaceful protest, which is an essential part of any healthy and functioning democracy," he said.

"The refusal of the organisers to co-operate with the police shows a contempt for peaceful protest and for democracy.

"The perpetrators of the violence and they alone are responsible for what ensued."

Mr Straw said eight officers had been injured in the clashes between police and protesters.

"I should like to place on record my appreciation and I believe the whole Houses for the way the City of London Police, supported by the Metropolitan Police, dealt with this outbreak of violence, which was plainly premeditated."

But the new Shadow Home Secretary, Ann Widdecombe, challenged the government to give guarantees it would not allow further cutbacks in the size of police forces.

The Carnival against Capitalism turned violent

The Corporation of London local authority estimates the cost of cleaning up after the violent demonstration will exceed £2m.

The number of people who took part in the Carnival against Capitalism has been put at between 6,000 and the 10,000 promised by its organisers.

Police have arrest six people following the violence, which included an attempt to storm the LIFFE derivatives exchange, on a range of charges.

Further arrests from a follow-up operation based on viewing CCTV footage have also been promised.

As the clean-up effort got under way on Monday morning, the owner of one restaurant in the area expressed surprise at the scale of the damage.

"It took us by surprise, we never expected anything like this. It was an assault," said Kamell Tilouche, chef and owner of Le Quai.