A powerful committee of MPs has said ministers are "confused" over plans to encourage pupils to walk to school.

In a report on the draft School Transport Bill released on Wednesday, the Commons education committee claimed the initiative is at odds with the government's bid to introduce parental choice over where pupils are taught.

While the legislation aims to cut down on "school run" car trips by asking local authorities to trial walking, cycling and public transport schemes, the Department for Education and Skills is also pressing ahead with reforms designed to widen the areas in which children can travel to school.

The MPs found that the two positions are incompatible, with a larger choice of schools inevitably meaning more pupils have to travel further away from home.

"The government seems confused as to the objectives of its draft bill," the committee concluded.

"The secretary of state has said that it will encourage more children to walk or cycle to their local school, yet this does not sit easily with government policies to increase diversity in schools and to allow for the expression of parental preference: an approach that encourages greater mobility."

At present the law requires local education authorities to provide free travel to children in cases where they live more than a "reasonable" walking distance away from their nearest "appropriate" school.

The committee argued that the government was right to want to refocus the resources spent on this policy towards the poorest pupils' transport.

But factors such as the right to go to a particular faith school and the creation of specialist schools have complicated the issue as to what constitutes a "reasonable" distance or "appropriate" school.

The MPs called for a re-think of the bill before it is brought back in its full form.

"The draft bill's central proposal to pilot schemes tailored to local circumstances, which may include charging, is sound," the report said.

"It must be accompanied by a more radical overhaul of legislation, which would allow schemes to adapt school transport strategies to today's social and technological context."