The amount of NHS money spent on anti-obesity drugs in Scotland has risen to almost £5m a year to fund a five-fold increase in prescriptions for overweight patients.

New figures out yesterday revealed that in the past 12 months more than 100,000 prescriptions have been handed out for drugs to treat obesity - up around 14,000 or 16% on the previous year.

The growth, to five times the prescribing rate in 2001, has pushed NHS spending on the drugs up by around £750,000 in a year from £4.12m to £4.89m between 2005-06 and 2006-07. Greater Glasgow, Lanarkshire and the Western Isles health boards spent the most per head on obesity drugs at £1.36, £1.41 and £1.87 respectively.

Opposition MSPs called for greater action from ministers to tackle Scotland's "spiralling" obesity problem, which is the worst in Europe and second-worst in the world.

The Scottish Government admitted that the issue was worsening and pledged to take action to tackle the condition, which increases the risk of a range of health problems including diabetes, heart disease, strokes and cancer.

Minister for Public Health Shona Robison said: "The Scottish Government recognises that obesity is an increasing problem and poses a serious threat to health. This is why we are taking steps to avert the onset of unhealthy weight, particularly early in life, as a high priority.

"Over the next three years we will be investing £56.5m, of which £40m is new money, in initiatives dedicated to tackling obesity, healthy eating and physical activity."

The government is also publishing an obesity action plan later this spring outlining details of projects to build on its existing diet action plan and physical activity strategy.

Commenting on concerns about the amount of cash being spent on obesity drugs, Ms Robison added: "For people who do become obese, support through diet, physical activity and lifestyle advice is the priority. But we also recognise that for a small minority this will have no effect on their weight. In such cases a clinical decision to prescribe drugs, based on the specific health interests of the patient, may be the most appropriate step to take."

However, Mary Scanlon MSP, Conservative Shadow Cabinet Secretary for Health and Wellbeing, said: "The situation is fast spiralling out of control. We need to start educating people about the dangers of an unhealthy lifestyle, starting with mothers in ante-natal classes. There needs to be awareness of the damaging effects created by a poor diet and insufficient exercise."