One of the country's most commonly prescribed anti-obesity drugs has been banned across Europe after it was blamed for increasing patients' chances of suffering a heart attack or a stroke.

The European Medicines Agency (EMA) ordered doctors across the continent to stop prescribing sibutramine and told pharmacists not to dispense the drug, which is marketed in the UK as Reductil.

The watchdog's Committee for Medicinal Products for Human Use (CHMP) acted after a study of 9,800 patients said the risks of sibutramine outweighed its minimal benefits.

About 86,000 people took the drug last year. It is prescribed alongside lifetsyle changes for patients who are classed as clinically obese, because they have a Body Mass Index of at least 30, and also in profoundly overweight people who also have a condition such as type 2 diabetes or abnormal levels of fat in their blood.

Users should not worry and should arrange to see their family doctor to be put on an alternative treatment, according to EMA advice last night, which was endorsed by the Medicines and Healthcare products Regulatory Agency (MHRA).

Dr June Raine, from the MHRA said: "Evidence suggests that there is an increased risk of non-fatal heart attacks and strokes with this medicine that outweigh the benefits of weight loss, which is modest and may not be sustained in the long term after stopping treatment."

Anyone currently using the weight-loss aid should not face any implications for their health if they decided to stop taking it before seeing their GP, Raine added.There has been concern about the safety of sibutramine since it was first licensed for use in the EU in 1999. Initially it was felt that the drug's benefits overrode the risks involved.