The number of patients undergoing weight-loss stomach surgery has increased by 41 per cent, prompting claims the Government is not doing enough to persuade people to change their lifestyles.

More than 3,400 gastric bypass operations for obesity were carried out in 2006-07, marking a huge rise over the previous year, according to figures published in Parliament.

The highest number of operations were in Hull, with 207 undertaken by Hull and East Yorkshire NHS trust in 2006-07, compared with 115 the year before, a rise of 80 per cent.

Other big rises were recorded in Aintree, Merseyside, up 171 per cent from 14 cases to 38; Cambridge up 130 per cent from 23 cases to 53; and Manchester, up 177 per cent from 13 cases to 36. The figures suggest obesity remains a national problem.

Although, the operation, which reduces the size of a patient's stomach so they are unable to digest large amounts of food, remains relatively rare, the figures show more hospitals are carrying out the surgery for the first time on the NHS.

Growing fears about the health risks of obesity, including cancer, could driving more patients to seek drastic help to lose weight.

The shadow Health Secretary Andrew Lansley said: "These figures reflect the cost of obesity. Gastric bypass surgery is a last-ditch solution and the number of operations will continue to rise sharply in the future unless we do a lot more to encourage people to be more active and eat more healthily.

"The Government is failing on reducing obesity, which is sadly unsurprising given that public health budgets have been cut."

The Department of Health rejected the criticism and said it was planning a £75m campaign to tackle obesity. It will be aimed at persuading people to change their eating habits and to take more exercise.

Officials said it was for doctors to determine the most appropriate methods to deliver health care to patients, based on clinical need and effectiveness. "Surgery is always a last resort when all appropriate non-surgical measures have been tried," said a spokesman.