David Cameron, the prime minister, said on Wednesday that the police "fightback'' against rioting was succeeding as the presence of 16,000 officers on the streets of London had dampened violence across the capital on the fourth night of unrest.

Speaking from the steps of Downing Street after chairing a meeting of the Cobra security committee, Mr Cameron said that "every contingency [was] being looked at", and "nothing [was] off the table".

"The police are already authorised to use baton rounds, and we agreed at Cobra that while they are not currently needed, we now have in place contingency plans for water cannon to be available at 24 hours' notice," he said.

Mr Cameron added that the lack of responsibility and disregard for others displayed by the rioters showed that pockets of British society were "not just broken, but frankly sick".

On Tuesday night, three people were killed as the riots and looting spread beyond the capital.

West Midlands police said they had arrested one person and launched a murder inquiry after three people - said by friends to be protecting their neighbourhood from violence - were hit by a car in Birmingham's Winson Green.

David

Cameron has been briefed by the Metropolitan Police that most of the

people taking part in London's riots are hardened criminals, according

to Downing Street sources.