Iain Duncan Smith has accused the government of being more concerned with "gimmicks" than actually reducing crime.

Following four announcements on crime over the last seven days, the Tory leader said: "In the last week the government has announced a new target for violent crime by September, docking child benefits from truants, putting police into schools and giving London 700 more police."

"Given that the local elections are tomorrow doesn't he feel that it is any wonder that the public are cynical about such gimmicks," he asked.

Tony Blair hit back insisting the announcements were part of a concerted campaign to tackle crime.

"These are part of a continuing series of measures to deal with every single aspect of youth crime," said Blair.

"The difference is that we are trying to deal with this issue whereas every single one of the proposals we have made they have opposed."

Duncan Smith was unimpressed. "The reality is that he has announced extra police officers seven times in the last five years," he said. "As many people are leaving the Met as are joining it."

The Tory leader said the announcement of extra money for policing in London would equate to just two officers per London borough.

"When will he understand that they don't want gimmicks they want crime to be stopped," said Duncan Smith. "Out there people know that violent street crime is rising."

Blair insisted he was taking action to tackle crime and challenged the Tories to back his strategy.

"The difference is that we are sitting down with the police and others in our criminal justice system working out each and every measure we need to take to tackle these problems and he is opposing them," he said.

Liberal Democrat leader Charles Kennedy also confronted the prime minister on his proposal to withdraw child benefit from the parents of persistent young offenders.

With reports suggesting senior cabinet ministers are opposed to the plans, Kennedy asked: "Which members of the cabinet actually do support the prime minister's plan to withdraw child benefit from the parents of persistent offenders?"

The prime minister responded that the government was merely working on the policy. "When we have a firm proposal we will put it before people, however, as we said we are examining this," he said.

He said housing benefit payments would also be looked at and challenged his critics to make it clear if they were opposed to tackling the problem.

But Kennedy accused Blair of planning another "half-baked" idea.

"Isn't this idea going to go the same way as that half-baked idea to take youngsters along the streets on a Saturday night to the nearest cash machine to pay their dues to society? Wouldn't it be better to bury this here and now, for once and for all?" said Kennedy.

Blair said that fixed penalty notices were now law and the government "will take whatever measures are necessary to crack down on this issue".

He said all Labour MPs were behind him in tackling the problem of anti-social behaviour.

The prime minister said the government would make sure parents took responsibility for the behaviour of their children.