Man shot during London riots dies

Police were caught off guard and emergency services stretched by the rapidly expanding violence that has reportedly been organised on social networks including Twitter and Blackberry messenger.

Australians tell of violence

An Australian in Hackney, Damian Cavanagh, said police were being careful to avoid clashing with rioters.

"At one stage the front line was 15 or 20 officers (who) backed away from one individual who was advancing on them," the 30-year-old said.

"I think they are aware how quickly actions by them could inflame the situation."

Australian journalist James Scurry said parts of the city were "like a war zone".

"There were cars reversing along a major highway. They were trying to escape the violence," he said.

"These types of things just don't happen here in London."

Clapham north resident Lucy Antoniou told the Herald Sun there was looting down her street.

"Our big department store, Debenhams, in Clapham Junction, has been completely trashed and looters have taken everything," she said.

Ms Antonious said many affected areas were without police as law enforcement was stretched thin over the city.

The Australian Department of Foreign Affairs and Trade is warning the more than 50,000 Australians in London to avoid all demonstrations and protests.

Australians are also being cautioned against travelling to London and other riot-torn cities.

A travel advisory issued by the Federal Government's Smartraveller website this afternoon has warned of unpredictable violence, rioting and fires throughout the UK.

How it began

The bulk of the violence began on Saturday in Tottenham, north London, after 29-year old local man Mark Duggan was fatally shot by police on Thursday.

Mr Duggan's death stirred old animosities and racial tensions which prompted riots in the 1980s.

Tottenham was the scene of severe rioting on the Broadwater Farm housing estate in 1985 when police constable Keith Blakelock was hacked to death.

The latest riots did not seem to be fuelled by a need for justice or revenge.

"All they want is a free TV or a new pair of running shoes. They're just taking whatever they fancy. These people are evil," one East London witness said.

As the unrest spread, some pointed to rising social tensions in Britain as the Government slashes STG80 billion ($A129.0 billion) from public spending by 2015 to reduce the huge deficit, swollen after the country spent billions bailing out its foundering banks.

Police acknowledged that major new bouts of violence had flared in at least five locations, badly stretching their resources.

"The violence we have seen is simply inexcusable. Ordinary people have had their lives turned upside down by this mindless thuggery," police commander Christine Jones said.

The riots have also raised concerns about about security and policing ahead of next year's London Olympics.

Britain's Home Secretary Theresa May, who cut short her holiday to return to London, condemned the riots as "sheer criminality" and vowed that the perpetrators would face justice.

"The violence we've seen, the looting we've seen, the thuggery we've seen -this is sheer criminality," she said.

"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.

"Once again, I would like to pay tribute to the bravery of the police officers who put themselves in harm's way to protect the public, their property and local businesses."

Prime Minister Julia Gillard today condemned the rioters and said Australia wished its UK friends well and hoped the situation was brought under control as soon as possible.

"I, like many other Australians, have been very, very disturbed to see the images coming out of London," Ms Gillard said in Canberra.