"The vast majority of people on the streets of Paulsgrove last night were not concerned parents," he said.

Police guard the flat of the suspected sex offender

"They were people using the current debate over sex offenders as an excuse to carry out active disorder and violence."

More than 70 police officers were called to deal with the incident, which one witness described as a "minor riot".

The News of the World said the man was not on the Sex Offenders Register, as his offences were committed before the law came into force.

Superintendent Bob Golding of Hampshire Police said: "I don't believe he was on the register but we were fully aware of his whereabouts and activities."

'Total condemnation'

The newspaper condemned the attack, saying "unlawful vigilante action" was "wholly unacceptable".

"We readily reiterate our total condemnation of any such action," said a spokesman.

But it added that it stood by its "clear objective" to protect children.

Work went on throughout the night to clear up the damage.

Property of the targeted man was ransacked, and a police sergeant was hospitalised after being hit by a stone.

He shouldn't live on a housing estate where there are lots of kids and a school across the road

Portsmouth resident Linda Webb

No arrests were made on Thursday but police are studying CCTV footage of the event, which began peacefully before turning violent.

Jeff Wellings of Portsmouth City Council said that finding suitable housing for convicted sex offenders away from children or schools was impossible in Portsmouth.

He said: "If we don't know about [past criminal offences] then we're damned, if we do know we're damned. It's a no-win situation."

The News of the World campaign has been strongly criticised by police, social services and human rights groups.

Right to know

The newspaper - backed by murdered eight-year-old Sarah Payne's family - says parents have a right to know if they are living near someone who is a threat to their children.

That view was shared by some Paulsgrove locals. Mother-of-four Linda Webb said: "All the mums with kids have been saying they were going to do something and now they have.

"I don't think it's right that cars have been set alight but I do think it's right that they should get him out and he shouldn't live on a housing estate where there are lots of kids and a school across the road."

Police are protecting a 55-year-old south London man after 500 leaflets were distributed wrongly accusing him of being a child abuser.

They are also protecting a man in the Guildford area after he was wrongly identified as a convicted paedophile in a series of malicious letters.