London riots: residents cautioned over 'vigilantism'
The Metropolitan Police has warned Londoners against forming "vigilante patrol groups".
The caution comes after hundreds of residents in Southall, Enfield, Hackney and Eltham patrolled their areas.
On Tuesday night Sikh men in Southall, many with hockey sticks, stood guard outside a Sikh and a Hindu temple and a mosque following Monday's disorder.
Deputy Assistant Commissioner Stephen Kavanagh said "vigilantism" could lead to violence and drain Met's resources.
The Met described Monday's disorder as "the worst" in its recent history as violence began in Hackney and spread to Croydon, Clapham, Camden, Lewisham, Peckham, Newham, East Ham, Enfield, Woolwich, Ealing and Colliers Wood.
About 16,000 officers were on duty on Tuesday night - up from 6,000 - and the increased police presence will remain, the government said.
About 300 Sikh men gathered in Southall to protect religious buildings and businesses while about 100 men stood in Church Street, Enfield, vowing to "defend the streets".
Mr Kavanagh said: "I fully understand people's anger and frustration at what has happened.
"We have seen some outstanding acts of courage, youth workers, community leaders, teachers and alike taking to the streets with our officers to stop those people out there from breaking the law and persuading them to go home.
"What we don't need is for our resources to be diverted by groups of people, some of whom having been drinking.
"I do not support vigilantism and we do not want to see more violence on our streets," he added.
John Tully, vice chairman of the Metropolitan Police Federation, added that "individually" people have the right to self defence, "but I wouldn't go as far as to say that we should form vigilante groups to patrol the streets".
Satjinder Singh, from the UK Sikhs, told BBC News that they will guard Southall's streets until the "police can be there in time".
He said: "We started getting texts that there's a high probability of looters were going to try to attack Southall because of the high number of jewellery shops that are there and because of the proximity of the jewellery shops to the Sikh temple and other places of worship, the Sikhs felt it was essential for us to protect our place of worship.
"The feeling was that they (police) were spread so thin that there needs to be a community presence.
"And it is not vigilantism but it is effectively just protection of property."
Ken, who runs a small supermarket in Eltham, backed the people who came out to protect businesses.
"That is the only way you can stop the rioters."