As thousands of yobs took to the streets across the London districts including Hackney, Lewisham and Peckham, Scotland Yard's most senior officer called on parents to contact their children and urged the public to clear London's streets.
The fresh wave of violence also spread north to central Birmingham, with police saying shop windows had been smashed and looting had taken place.
Home Secretary Theresa May condemned chaotic scenes while Scotland Yard beefed up its presence before looting and violence spiralled out of control for a third consecutive night.
At least 215 people have been arrested and 25 charged following the riots across London over the last two days.
Acting Scotland Yard Commissioner Tim Godwin attacked the "gratuitous" violence and appealed directly to families.
He said: "I do urge now that parents start contacting their children and asking where their children are.
"There are far too many spectators who are getting in the way of the police operation to tackle criminal thuggery and burglary.
"I'm imploring that people within those communities actually start clearing the streets to enable my police officers to deal with the criminality that's occurring in front of them."
Mrs May said: "I think this is about sheer criminality. That is what we have seen on the streets. The violence we've seen, the looting we've seen, the thuggery we've seen - this is sheer criminality, and let's make no bones about it.
"That's why I say that these people will be brought to justice, they will be made to face the consequences of their actions and I call on all members of local communities to work with the police constructively to help the police to bring these criminals to justice."
A total of 153 arrests were made overnight and early this morning after boroughs in north, south and east London fell victim to the first round of copycat rampages following trouble in Tottenham on Saturday.
As skirmishes broke out again between police and hooded youths, Deputy Prime Minister Nick Clegg said "big scars" would be left from consecutive nights of rioting.
Scenes of violence in Hackney, Lewisham and Peckham echoed those in other areas of the capital over the past two nights, with skirmishes between gangs of youths and police, reportedly prompted by a stop and search incident earlier today.
In Hackney, rioters, many wearing hoods and masks, were confronted by police lines spanning the streets, occasionally moving forward to push the groups back.
Officers in riot gear tried to control the situation, coming under fire from objects including chairs and pieces of wood.
At one point several people broke into the back of a stationary lorry, pulling its contents out on to the road, with some hurling it at police and others using it to smash windows of a bus.
South of the river in Peckham, teams of riot officers were seen charging at fleeing troublemakers after a major fire was started at a shop adjoining a Greggs bakery.
A nearby bus was also set on fire while TV footage showed a trail of bins and an abandoned vehicle ablaze in Lewisham.
Croydon, Barnet, Streatham, Clapham and Islington were among a number of areas where shops were being advised to close early amid warnings they would be targeted.
A sign on the door of Tesco on Islington Green read: "Sorry, we have been closed by the police until further notice."
Deputy Assistant Commissioner Stephen Kavanagh said there would be a third more officers on the ground than there were last night, which was three times more than the previous night.
He said the force was getting police officers to Hackney "in numbers" to respond to violence in the area.
Opportunist rioters over the past two nights are believed to be aged from their mid-teens upwards, he added.
Last night's wave of looting was "disgusting behaviour, ripping apart people's livelihoods and businesses", he said as he vowed to deliver "speedy justice" for Londoners in the wake of the violence.
Mr Kavanagh also apologised to the family of shooting victim Mark Duggan - whose death sparked the original violence - for not managing their "needs" better as he warned that rioters "will not be tolerated".
He added: "Let me make it clear that people who are using current events as an excuse or cover to break the law, steal, attack police officers and cause fear to Londoners will not be tolerated by the vast majority of Londoners and us.
"Our investigation, which is massive in scope, is continuing. We are liaising with businesses and communities across London, including at a borough level, to keep people up to date with what we are doing."
Mr Clegg, who returned from holiday this morning, condemned the violence earlier as "completely unacceptable".
After walking down part of Tottenham High Road and speaking with business owners, Mr Clegg met local police chiefs, councillors and religious leaders.
Mr Clegg was joined by local Labour MP David Lammy and Home Office Minister Lynne Featherstone as he met Steve Moore, who lost his jewellery shop in Friday's violence.
Mr Moore said: "I'm devastated, it's completely gone. My shop just doesn't exist any more."
London mayor Boris Johnson interrupted his family holiday in North America and is returning to the capital to deal with the situation.
The fresh violence came after a peaceful protest in Tottenham on Saturday, which followed the fatal shooting of Mr Duggan, 29, on Thursday.
Last night's looting across London was carried out by "small and mobile" groups, Scotland Yard said.
Kit Malthouse, London's deputy mayor for policing, said the violence was perpetrated by a small group of people "looking for stuff to nick".
He denied that the resignations last month of Scotland Yard commissioner Sir Paul Stephenson and assistant commissioner John Yates in the wake of the phone-hacking scandal had contributed to gaps in decision-making at the top of the force.
Scotland Yard said at least nine officers were injured in last night's violence, including three who were taken to hospital after being hit by a fast-moving vehicle at 12.45am. The officers had been in the process of making arrests in Chingford Mount, Waltham Forest, after a shop was looted by youths.
Last night saw violence and looting in Brixton, Enfield Town and Walthamstow Central.
An inquest into Mr Duggan's death is due to open tomorrow at High Barnet Coroner's Court, the Independent Police Complaints Commission (IPCC) said.
The watchdog said it was awaiting "further forensic analysis" to gain a comprehensive account of the shots which led to his death.
The Guardian quoted a source as saying that initial tests suggested a bullet found lodged in a police radio after Mr Duggan's death was police issue.
The IPCC will publish details of ballistic tests in the next 24 hours.
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