Police are now patrolling a housing estate around the clock to protect the residents involved.

Officials at Islington Council in north London have described the blunder as "unforgivable" and are now trying to limit the potential damage caused by the "serious data leak" which has already led to harassment.

The bundle of evidence gathered in order to serve injunctions on 13 suspected miscreats - which would ban them from the Andover estate in Holloway - was delivered to 10 of the troublemakers along with the injunctions.

It is understood the details - including names, street names and phone numbers of 51 people in the area who had made complaints - had been photocopied in the council's legal department and stapled to the injunctions.

The Labour council's new crime boss, Councillor Paul Convery, said he was "furious" at the blunder which has set back the council's flagship drive against anti-social behaviour.

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He told the Islington Tribune: "In order to tackle anti-social behaviour we rely on residents coming forward as witnesses. Often they are scared. This has undermined their confidence in the system and we will be working very hard to get that confidence back."

The injunctions were served after months of evidence gathering last Friday. It only emerged on Thursday however that the confidential information had been served with them.

It is believed it came to light after one of the witnesses was called a "grass" as she was out with her children.

Cllr Convery said that police would now be on the estate 24 hours a day to prevent any further trouble. Officers had visited six of the 10 addresses where the information had been delivered to recover it and also to warn the youths involved of the "serious" consequences should they cause any trouble for the witness.

The other four were being tracked down "as we speak" he said last night. He reserved his full anger for the Town Hall's legal department, however.

"This should not have happened," he said. "There has been a lax procedure and security regime.

"These details should not even be on the log, never mind be accessed and photocopied by an absent-minded clerk. In other areas of the Town Hall, such as in child protection, you can't even log on to the computers."

"Management action" would be taken at a senior level, Cllr Convery added. "We are utterly gobsmacked by this," Cllr Convery added.

"We are going to have to do everything we can to restore public confidence as the co-operation of the public is the only way to tackle anti-social behaviour."

A Town Hall spokeswoman said last night that the police had already recovered six of the 10 bundles and that they were in the process of contacting the 51 people whose details had been leaked.

"We will assist them in any way we can, including helping them with changing their phone numbers if necessary," she said.

The spokeswoman added that the troublemakers were "low level" and rather than being violent or gang members had been causing nuisance by playing music too loudly or verbally intimidating residents.

Louise Round, Islington Council's corporate director of resources, said: "This information should not have been released, and we are extremely sorry that, through an error on our part, it has been disclosed. "

The council is in the process of contacting every single person who is on that list - in total 51 people - to offer our apology and any practical support we can give. This includes additional security measures if they request it. We will also hold a detailed review of our admin processes to safeguard against this ever happening again."