The arrests of more than 200 leaders of London street gangs in the wake of last year's riots has led to an increase in "chaos, violence and anarchy" in the capital, a report claims.
Prime Minister David Cameron promised an "all-out war on gangs and gang culture" following the riots which brought mayhem to many English cities in the summer of 2011, and police have responded by arresting many of those associated with criminal groups.
But the report, by the Centre for Social Justice think-tank, warned that the removal of the so-called "elders" from the streets has backfired by creating a power vacuum in which younger and more hot-headed members seized control of gangs on a wave of violence.
Drawing on interviews with community leaders and former gang members, it warned of an "escalation" of violence as more junior members - known as "youngers" - vie for status and respect in the absence of the restraining hand of older figures who had imposed a code of behaviour.
"There was a consensus that the current gangs neither have such a code nor cohesive leadership, which is resulting in increased chaos, violence and anarchy," said the report by the CSJ, which was founded by Work and Pensions Secretary Iain Duncan Smith
It also reported a "startling" increase in the number of girl gang members and a rise in sexual violence within gangs, citing one case in which a 13-year-old girl involved with a gang was being sexually exploited by members and was grooming her own 10-year-old sister for the same purpose.
CSJ managing director Christian Guy said that the police crackdown after the riots had "created a Lord of the Flies environment in which anything goes".
He added: "Gangs played a significant role in the riots and it is dangerous to pretend otherwise - in London at least one in five of those convicted was a known to be part of a gang.
"The Prime Minister declared an all-out war on gang culture after the riots, which culminated in a radical strategy heavily influenced by the CSJ's own gangs research. But one year on political commitment is waning and the Government and local authorities have mistakenly assumed that its new strategy represents job done - it could not be more wrong.
"We have talked to members of our countrywide alliance of small, frontline organisations and charities asking them how they feel gang culture has changed in the light of the Government response. Worryingly many have drawn us a picture of little or no progress."