An extra 1,700 police officers were deployed in London, where shops were looted and buildings were set alight.
Birmingham, Liverpool, Nottingham and Bristol also saw violence.
The prime minister has returned early from his holiday to discuss the unrest, which first flared on Saturday after a peaceful protest in Tottenham over the fatal shooting of a man by police.
At least 450 people have been arrested following the riots across London over the past three days, the home secretary has said. Scotland Yard said 69 people had been charged with offences.
Three people were arrested on Tuesday on suspicion of attempted murder after a police officer was injured by a car in Brent, north west London, while trying to stop suspected looters.
In other developments:
* David Cameron will chair the government’s emergency committee Cobra to discuss the riots and will also meet Home Secretary Theresa May and Metropolitan Police Acting Commissioner Tim Godwin
* All tube stations in the capital that were closed due to the riots have now re-opened however there is a police cordon at one entrance to Ealing Broadway
* The Tramlink service between East Croydon and Wandle Park has been suspended as a result of the fire at Reeves Corner
* Elsewhere, 100 people have been arrested in Birmingham after scores of youths rampaged through the shopping area, smashing windows and looting from shops
* West Midlands Police also confirmed that a police station in Holyhead Road in Handsworth, Birmingham, was on fire
* There were reports of cars being damaged in Manchester and of up to 200 youths with masks roaming through Toxteth in Liverpool
* Police in Bristol said they were dealing with outbreaks of disorder involving about 150 people
* Nottinghamshire Police said a police station was attacked in the St Anne’s area overnight and 200 tyres were set alight in the street
Met commander Christine Jones said: “The violence we have seen is simply inexcusable.
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At the scene
Alix Kroeger BBC News, in Hackney
In a lane off Mare Street the wreckage of a burnt-out car still smoulders, surrounded by riot police.
I was talking to one young man who had received on his BlackBerry a list of places where he said there will be further trouble tonight.
He didn’t tell me which places and stressed it is speculation. But he and a friend told me frustration with poverty in the area was boiling over.
On Mare Street there is the sound of crunching as police vans run over broken glass. Much of it from a bottle bank which was overturned providing makeshift missiles for rioters who lobbed the bottles at police.
* Trouble in the heart of Hackney
“Ordinary people have had their lives turned upside down by this mindless thuggery. The Met will ensure that those responsible will face the consequences of their actions and be arrested.”
Monday’s violence started in Hackney after a man was stopped and searched by police but nothing was found.
In the first outbreak of violence, groups of people began attacking the police in Hackney at about 16:20 BST, throwing rocks and a bin at officers.
Police cars were smashed by youths armed with wooden poles and metal bars.
Looters also smashed their way into shops, including a JD Sports store, before being dispersed by police.
Nine police forces from other parts of the country assisted in providing support, as well as the City of London Police and British Transport Police.
However, eyewitnesses have reported that as trouble spread across the city, there were often few police officers around when violence flared.
Map of London riots
* Several fires broke out in Croydon, including one at a large sofa factory which spread to neighbouring buildings and tram lines
* In Hackney 200 riot officers with dogs and mounted police were located around Mare Street where police cars were damaged
* Looters raided a Debenhams store and a row of shops in Lavender Hill in Clapham, as well as shops in Stratford High Street
* Police used armoured vehicles to push back more than 150 people in the Lavender Hill area
* A Sony warehouse in Solar Way, Enfield, a shopping centre in Woolwich New Road, a timber yard in Plashet Grove, East Ham and a building on Lavender Hill were all on fire
* More than 100 people looted a Tesco store in Bethnal Green, the Met said, and two officers were injured
* Cars were set on fire in Lewisham
* A bus and shop were set alight in Peckham
* Buses were diverted as the violence spread to Bromley High Street
* There were reports of looting of phone shops in Woolwich High Street, in south London, and a torched police car
* Shops and restaurants were damaged in Ealing, west London, and there was a fire in Haven Green park opposite Ealing Broadway Tube
* Football matches at Charlton and West Ham which were due to be played on Tuesday have been postponed at the request of the police
* At Clapham Junction looters stole masks from a fancy dress store to hide their identity
* Police found a 26-year-old man in a car in Croydon suffering from gunshot wounds. He is in a serious condition in hospital
The fresh violence prompted the Met’s Acting Commissioner Tim Godwin to call on parents to contact their children and urge the public to clear London’s streets.
Looters in a convenience store in Hackney Shops have been looted across the capital
Catherine Holmes, a resident in Hackney, said: “The common feeling in Hackney Central is that our community has been hurt and damaged by causeless violence.
“We spoke to looters trying to get home, the only explanation they gave for their behaviour was that they had no money today.
“It is sad to think that these people are thinking of only the next moment, and the moment they have created is a nightmare. As we watch them now moving on in small pockets, we hope that our community will unite together this morning to react against these riots.”
Ealing resident Christian Potts, 29, was driving through the area when he witnessed the disturbances.
“It looks like a war zone – I have never seen anything like it in all my life,” he said.
“There were about 25 to 30 masked youths on Haven Green and they just started tearing into a florist with bricks.
Clapham resident Nick Shaw escaped unhurt from his home which was set ablaze
“It’s a local family-run business so I can’t see why they are doing this.”
London’s mayor Boris Johnson is cutting short his holiday to return to the city.
Home Secretary Theresa May also returned early from holiday, to meet Met chiefs to discuss their response to the violence.
“These have been the worst scenes of violence and disturbance on our streets for many, many years, and this sort of violence, this level of criminality, this thuggery, this looting, this theft, is completely unacceptable,” Ms May told BBC Breakfast.
“We can deal with it. We can deal with it with robust policing, with good use of intelligence, but also with the help and support of local communities.”
She added: “If there’s anybody who knows somebody who was out on those streets last night and involved in this action then they should tell the police.”
The trouble follows two nights of violence over the weekend which started after police shot a man dead in Tottenham.
A peaceful protest in Tottenham on Saturday over the fatal shooting by police of Mark Duggan, 29, was followed by violence which spread into Sunday.