They hope the technique will become a less traumatic alternative to surgery, and offer treatment to patients whose tumours are deemed to be inoperable.

The technique, known as radio-frequency ablation, has been developed by US cancer specialists John McGahan and Philip Schneider, and is described in New Scientist magazine.

So far the technique has been used to treat liver cancers - which are usually fatal, but is likely to work for other types of tumour.

To treat liver cancers, a flexible catheter is inserted through the patient's abdomen, using an ultrasound scan to guide it into position against the tumour.

A cluster of eight to ten wires is fed through the catheter, and at the end of the tube they fan out and penetrate the tumour.

A very high frequency current is passed through the wires, causing the tumour tissues to heat up from within.

After ten minutes cells in a region measuring three to five centimetres across are killed.

The technique can be used to destroy up to five liver tumours in a single session.

Patients can also leave hospital much sooner than those undergoing conventional surgery.

Serious side effects

Professor John McGahan has developed the technique

However, the technique does have serious side effects as biochemically active substances can leak from the dead tumour cells into the rest of the body.

As a result, patients may become feverish or nauseous.

The treatment may also damage nerves near the liver's surface, resulting in chest or abdominal pain for up to a week.

The treatment has so far been tested on 12 patients, of which nine have been free of cancer for more than a year.

However, several more years of evaluation are needed before the treatment becomes widely available.