A "health tax" could be slapped on food such as crisps and fizzy drinks sold at Bradford's hospitals in a bid to improve health.

Drinking water will also be made available free of charge as an alternative to sugary pop as part of Bradford Teaching Hospitals NHS Foundation Trust's commitment to reducing levels of obesity.

Health chiefs have also pledged to make surgery available for obese people, as part of a full range of services to help people lose weight.

It follows plans by Bradford Council's Health Improvement Committee to appoint a health tsar to tackle obesity in the district and help slim down the district.

The new healthy eating strategy, where the "health tax" will be used to subsidise the cost of fresh food and fruit, is contained in a blueprint produced by the Foundation Trust which sets out the way forward for Bradford Royal Infirmary and St Luke's Hospital until 2010.

Hospital bosses believe they have neglected for too long their role as a centre for healthy living and want to become not just a "sickness service" but an organisation at the forefront of promoting health.

It follows a total ban on smoking within the hospitals' grounds which came into force in on January 1.

Dean Johnson, the Trust's director of performance and planning, said: "We were one of the first hospitals in the country to develop a public health strategy and this corporate strategy was an opportunity to see how we could take it further.

"The idea is to encourage people to eat healthier on the hospital site so rather than having crisps they could have yoghurt or healthy products like that.

"It is about doing more to provide healthy food cheaply and we want to see what people think of it."

Councillor Elaine Byrom, chairman of Bradford Council's Health Improvement Committee said: "I think it is laudable they are coming up with something that will get rid of fattening foods, such as crisps.

"Obesity is the root cause of many illnesses, such as diabetes and heart disease, and I applaud their concern about the type of food available to patients and visitors."

However, Colin Sloane, chairman of Patient and Public Involvement Forum for Bradford Teaching Hospitals said he thought the move could be seen as controversial.

"It is dictating to people what they cannot eat," he said. "I have had the same argument with them about the smoking ban they have implemented which bans smoking everywhere in the hospital, even the hospital grounds.

"I have had a long argument about cancer patients not being able to smoke. When they have been diagnosed with six months to live there is little point in them stopping smoking - but the Trust would not budge.

"It does have a role to play in public health but it is how far it takes that that concerns me."

Mr Sloane, who will step down as chairman of the PPI Forum after its next meeting in January 12, said he was concerned the ideas in the five-year-strategy were being imposed on patients and the public with little discussion.

He said he will raise this issue with Mr Johnson, who will present the corporate strategy to the PPI Forum at its next meeting.

"The main thing I will point out is that within the strategy there is a great deal of talk about what the Trust will do for the patient but there is not enough about how patients and the public will be involved in making decisions," said Mr Sloane.

The full corporate strategy can be viewed at www.bradfordhospitals.nhs.uk where feedback can also be given until January 11.