Hospital food worth more than £144m is thrown away every year because it is cold, unsuitable or plain inedible, according to a report by leading nutritionists.

Around five million NHS meals are prepared every day. Yet two million of those are not eaten - because the quality is so low or because patients are too ill to consume them, or because they have simply ordered a takeaway.

According to the British Nutrition Foundation, hospital catering is so poor that some patients actually become clinically malnourished during their stay.

Ministers have now ordered hospital kitchens to improve the quality of food and are set to introduce tough new guidelines in the autumn. In a move that turns the clock back 20 years, doctors and nurses will be put back in charge of patients' diets, bringing to mind Florence Nightingale's dictum that "mealtimes are sacrosanct". And if hospitals get it wrong, government inspectors will issue fines and bring in better quality staff.

The NHS is already struggling to cope with the effects of poor diet in the general population. An estimated 40 per cent of elderly patients and 15 per cent of children arriving at hospital are malnourished. According to the Nuffield Trust, an independent health think-tank, malnutrition adds a further £300m to the NHS bill.

The national service framework - an enforceable programme for all aspects of care of the elderly, including food - will make doctors, nurses and hospitals' chief executives responsible for providing nutritious food as part of the whole package of care.

Columnist and former nurse, Claire Rayner, who is the president of the Patients' Association, said yesterday: "The situation is highly unsatisfactory. There's no variety, the food is utterly dreary and bland and patients simply don't like it. It's not attractively served either - contract catering staff simply come around and plonk a tray down. If a meal arrives while a patient is off having an X-ray, the catering staff will simply leave the tray there until it is cold."

In some cases, hospital food has been positively dangerous. A food poisoning outbreak at a hospital in Wakefield, Yorkshire, in 1986, killed 19 elderly patients. And detectives are still investigating allegations dating back to 1997 that 30 elderly patients died because they were deprived of food and water by staff at the Rowsley psycho-geriatric ward at Kingsway Hospital in Derby, Derbyshire.

A senior NHS manager, who did not want to be named, said he was surprised that more scandals had not emerged. "The problem is that NHS food is very poor quality," he commented. "You get three meals a day and seven cups of tea per patient for about two quid - some do it for £1.50.''

Kings College Hospital in south London has already started to tackle the problem. It spends £2.7m a year preparing meals for 1,000 people a day. But around 40 per cent of the food was being wasted due, in part, to the quarter-mile journey from the central kitchens in the bowels of the hospital to some patients' bedsides.

"Cooks were meant to prepare eight tray meals every minute. It was just a question of getting things on a plate as quickly as possible,'' said Rick Wilson, the hospital's director of nutrition and dietetics. Now each ward will get its own host or hostess, provided by a private contractor, to prepare food for 20 or 30 patients.

"Hosts and hostesses will get to know what people like, if they are feeling particularly hungry or not so they can tailor the meals to suit appetites. In that way, there is less waste and people do eat more. Now we expect 20 per cent wastage in the first year rather than 40 per cent,'' Mr Wilson said.

A spokeswoman for catering and services company Sodexho which has contracts with 130 NHS hospitals, denied that privatisation caused waste.

"We run very successful contracts across the NHS and provide a whole range of services trying to work with local hospitals to provide food on the premises or in pre-cooked form," she said. "We also provide dedicated dieticians to ensure meals are balanced.''