Tories called the scheme an "unaffordable luxury|"

Roger Evans, deputy chairman of London Assembly's transport committee, wants to scrap the scheme amid concerns of growth in anti-social behaviour.

The Conservative has said the subsidy, which has cut bus fare revenue by �55m a year, was an "unaffordable luxury".

Mayor Ken Livingstone said: "I can't think of a more spiteful policy since the removal of free school milk."

Helping families

He said the polls showed eight out of 10 Londoners support the policy of "helping families by making bus travel for children free".

Countless commuters have told me their experiences of anti-social behaviour have been more frequent Roger Evans

"I will fight all the way, any plan to abolish free bus travel for children, which was one of my key election commitments in 2004," the mayor said.

"The proposal to abolish free bus travel would cost many families hundreds of pounds a year and hit the poorest families hardest."

Mr Evans said he had "serious concerns" about the policy contributing to anti-social behaviour.

"Countless commuters have told me their experiences of anti-social behaviour have been more frequent," he said.

He supported alternative solutions to the current policy such as a school bus scheme or a curfew on the free-bus scheme.

Bus journeys made by children have increased from 252 to 300 million since the scheme was introduced in September 2005.

Despite a 5% shortfall in earnings because of the scheme, bus fares revenue in 2007 is expected to be in excess of �1billion.

"We are investing �10billion over five years to improve and expand London's transport network," said a spokesman for the mayor.