Thousands of low income families are to receive vouchers for free fruit and vegetables in a bid to tackle the rise in childhood obesity, the health secretary, John Reid, said today.

Announcing the scheme - a week after three medical bodies classed 9% of children aged two to four as obese - Mr Reid said it would encourage children to eat a healthy diet from an early age.

Under the reform of the welfare food scheme, which currently provides tokens for milk and baby milk formula, some of the poorest pregnant women and families will receive weekly vouchers, which can be used to buy fruit and vegetables as well as milk.

Mr Reid said: "The best way of tackling obesity is through encouraging a healthy diet at an early age.

"These changes mean that pregnant women, nursing mothers and younger children already benefiting from the [welfare food] scheme will in future have a greater choice of healthy eating options, so reducing the chances of obesity."

A Department of Health (DoH) spokesman added that the reforms will also mean children in nursery will be offered a choice of milk or fruit, instead of just milk as happens at the moment.

He estimated that up to 800,000 people on low income or in receipt of tax credits will benefit from reform of the scheme, which will be phased in from the end of 2004.

The vouchers will be worth at least £5.60 a week to families with children up to one, and at least £2.80 a week to families with children over that age.

All pregnant women under the age of 18 will also be eligible for the scheme, regardless of family income.

The health secretary's announcement follows last week's call by leading doctors for the government to put together a coherent strategy to fight the UK's obesity epidemic.

The joint report by the Royal College of Physicians, the Faculty of Public Health, and the Royal College of Paediatrics and Child Health stated that obesity among children aged two to four had almost doubled between 1989 and 1998, from 5% to 9%.