THE Prime Minister yesterday set out radical plans to identify children who could become teenage troublemakers before they are even born.

Tony Blair said dysfunctional families would face earlier state intervention to prevent their children becoming "a menace to society".

In his first remarks since returning from holiday, Mr Blair said action had to be taken "pre-birth" if necessary and defended the need for state intervention.

"If we are not prepared to predict and intervene far more early, then there are children that are going to grow up in families that we know perfectly well are completely dysfunctional," he told BBC News 24.

"The kids a few years down the line are going to be a menace to society and actually a threat to themselves."

Mr Blair, who earlier this week led a seminar on social exclusion with ministers and experts, is due to make a speech on the issue on Tuesday.

Yesterday's proposal is believed to have come out of that meeting at Chequers, and a Government policy paper on the issue is due to be published soon.

The Prime Minister said: "You either steer clear and say that's not for Government to get into, in which case you don't deal with the problem," he said.

"We need to deal with these issues and we actually do intervene and we intervene at a very early stage.

"If you've got someone who is a teenage mum, not married, not in a stable relationship (we say), 'Here is the support we are prepared to offer you, but we do need to keep a careful watch on you and how your situation is developing because all the indicators are that your type of situation can lead to problems in the future'."

Mr Blair said that earlier intervention marked the next stage in Government policy to help the poorest families.

"What I'm really talking about now is a group of people that maybe have multiple problems who we need to identify far earlier and who the general policy - the New Deal, Sure Start, the investment in the schools and so on - really hasn't helped," he said. "Children's tax credit, the New Deal and Sure Start have helped hundreds of thousands, millions of people, but you've always got to be looking at the next stage."

The Prime Minister expressed confidence that the work would outlast his time in Downing Street.

"For us as a party and a Government, this is something we are passionate about, that we have developed for a number of years and will continue long after I've gone," he said.

"I think most sensible people, whatever their political persuasion, will say, yes, this is a debate we need to have."

Tough action to deal with potential yobs at an early age was floated by then Home Office Minister Hazel Blears at Labour's annual conference last year.

She said that doing nothing despite the warning signs was "like watching a slow train crash".

But she was talking about toddlers - a stance Mr Blair took much further yesterday.

The Prime Minister will take his message to the streets on Monday when he makes a regional visit on the eve of his speech. Social Exclusion Minister Hilary Armstrong will set out an action plan the following week.

Last night, Oliver Letwin, chairman of the Conservative Party's policy review, said: "The answer is not more state intervention. It is to encourage the voluntary sector, community groups, to help people without trying to run their lives for them."