Speaking in Downing Street after chairing a meeting of the Government’s Cobra emergency committee, Mr Cameron said: “We needed a fightback, and a fightback is under way.”
He said officers would be given the resources and legal backing to use the tactics they felt were necessary to deal with the riots.
“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 cannons to be available at 24 hours’ notice,” he said.
In a major break with the government, the Tory London Mayor Boris Johnson yesterday demanded a rethink of plans to slash police budgets by 20%.
The mayor, who is seeking re-election next year, told the BBC: “That case was always pretty frail and it has been substantially weakened. This is not a time to think about making substantial cuts in police numbers.”
But Mr Cameron brushed off Mr Johnson’s concerns, insisting forces had all the resources they required.
Thousands of extra police officers in London helped quell trouble on the capital’s streets on Tuesday night, but ugly scenes of violence spread to other cities.
Yesterday afternoon police arrested an 18-year-old man on suspicion of arson over the blaze in Manchester’s Miss Selfridge store.
And two of those arrested have already been jailed in what Greater Manchester Police said was “swift justice”. “Two men sentenced to 10 weeks and 16 weeks. First of many,” the force warned.
Trouble also broke out on Tuesday in Nottingham, Leicester, Wolverhampton, Gloucester, Bristol and Toxteth in Liverpool.
Birmingham residents seethed with anger at the hit-and-run death of three men who were defending local businesses, but confrontations with police have not escalated into violence.
A group of around four men, flanked by another 50, were seen arguing with a police officer, who did not raise his voice and slowly walked away from the group.
One man said loudly to the officer: “What would you do if you lost a son?”
Another said to a reporter: “We’re not causing tension, we’re just raising our concerns.”
In Manchester, a large police presence and heavy downpours appeared to have acted as a deterrent to looters returning to the city centre.
The Arndale Centre closed early, at 5pm, while many other shops, bars and restaurants chose to do the same. The Tesco Metro store was the only shop in the centre’s busiest shopping thoroughfare, Market Street, to remain open.
Riot police were not on the streets but officers in high-visibility jackets were dotted around in large numbers throughout the centre.
Many patrolled in groups of two and three. Others were stationed at flashpoints of Tuesday night’s violence.
Senior police officers played down the prospect of using water cannons against rioters.
Hugh Orde, president of the Association of Chief Police Officers, oversaw the use of the weapon when he was head of the Police Service of Northern Ireland: “They were vital in Northern Ireland. At the moment I don’t see a need in the rest of the United Kingdom.”
There is widespread support across Britain for the use of water cannons, firearms and even Army involvement to help deal with the situation, according to a survey published yesterday.
But amid heightened attention over the use of kettling tactics and the conduct of officers at disturbances, including the G20 and fees protests, forces are wary of allegations of brutality.
Speaking after Mr Cameron’s call for a “fightback”, Mr Orde said it was crucial to keep policing separate from politics: “It’s not actually a matter for the prime minister, it is a matter for chief constables.
“One of the great strengths of British policing is it disconnects policing from politics.”
Nine out of 10 British adults say police should be able to use water cannon on rioters and one third support the use of live ammunition, according to a YouGov poll commissioned for the Sun newspaper.
The poll found more than half the public believe the police were dealing with the situation either “very well” or “fairly well”, while just over a quarter (28%) felt Mr Cameron was dealing with the situation well.
Joe Twyman, a researcher at YouGov, said: “It is clear from the data that a majority of the population feels that politicians have handled the unrest badly so far.
“There is also significant support for making a wide range of new tactics available to the police. However, this is clearly a rapidly changing situation and we shall continue to monitor public opinion to investigate how things develop.”