The new treatment, reported in The Lancet, could improve the quality of life for many sufferers who endure epileptic seizures every day, and are not helped by conventional medicines.

Researchers at Gottingen in Germany used a coil which was placed on the side of the head to direct the magnetic pulses to the brain.

The use of high-frequency pulses has been blamed for triggering epileptic seizures, and this is some of the first work using low-frequency magnetism.

The nine patients in the Gottingen study suffered an average of more than 10 fits a week but, after the magnetic treatment, nearly all suffered fewer seizures.

One patient showed a 20% decrease, three improved by between 20% and 50%, and in three patients, the number of seizures was reduced by more than half.

Only a temporary effect

However, the effects of the treatment wore off after six to eight weeks, and two patients suffered "petit mal", or partial seizures directly after treatment.

Professor John Duncan, medical director of the National Society for Epilepsy, said the treatment had potential for wider use.

He said: "It certainly sounds very interesting. Magnetic stimulation has been around for some time.

Epilepsy is caused by overactivity in parts of the brain

"The problem has always been that high-frequency magnetic stimulation may cause seizures, and I have not heard the use of low-frequency reported before in people with epilepsy."

Epilepsy is caused by overactivity in one part of the brain, which overloads the nerve "circuitry" and causes seizures.

The areas most usually affected are the temporal lobes, at the side of the brain and the frontal lobe.

Distracted appearance

There are two types of fit. One, the partial seizure, is associated with a change in consciousness - often the only external clue of a seizure is that the person affected will merely appear vacant or distracted for a short period.

Partial seizures often originate in the temporal lobe, which is associated with memory, and patients often report experiencing a familiar smell, sound or mental image shortly before, or during the seizure.

The other, more serious seizures are convulsions or "grand mals", which can strike without warning and cause unconsciousness and jerking movements.

Treatment of both sorts of seizures is usually with drugs, which can control the number and severity of seizures suffered.

Operation is last resort

If drugs fail to work, other options include brain surgery, cutting out the part of the brain where the overactivity generally starts - but this is a last resort for doctors.

It is thought that up to a quarter of the 30,000 people in the UK who develop epilepsy every year are poorly controlled by medication.

Magnetic stimulation has also been used in the field of mental health where recent research has found it to alleviate some cases of depression.