London, July 24 : Scientists at a British laboratory have developed two pills which can halt the spread of skin cancer by shrinking deadly tumours by half.

Scientists at the GlaxoSmithKline drugs firm say the pills - which could be available within three years - will improve the length and quality of life for those with malignant melanoma, the deadliest form of skin cancer, the Daily Mail reported.

Malignant melanoma is the "most quickly rising" cancer in Britain, with around 10,000 new cases and 2,000 deaths each year. Rates have doubled in the last two decades, because of excessive tanning by British people on holidays to hot countries.

It is now the most common form of cancer in women in their 20s. Around 340 women are diagnosed every year, 50 of whom die.

The cancer tumour, which first manifests itself as a small mole on the skin, can be surgically removed if detected early. But once it spreads to other parts of the body, it is usually terminal. Patients can be given chemotherapy to control it, but it will not stop the disease from advancing.

Now scientists have claimed that a daily dose of two pills could halt the cancer in its tracks by shrinking tumours, even in the most advanced stages.

The drugs target the harmful protein which causes the tumours to grow in the first place. By disabling the protein, the drugs stop the spread of cancer and can even reverse its growth - although tumours cannot be removed altogether.

The researchers carried out a series of trials on 80 patients with advanced skin cancer. They found that more than half of patients who took the first drug, called "Braf 436", saw their tumours reduced by at least 20 percent.

Tumours also shrank in more than half of patients who took a second pill, "Mek 183". In a quarter of patients they reduced in size by 50 percent.

The scientists will now carry out trials on people taking both pills at the same time.

"What we want to do now is see the effects of these two drugs taken in combination. We don't yet have the answers but we believe they will be very promising," Peter Lebowitz, vice president of clinical development at the drug firm, was quoted as saying.

Although patients would not be completely cured, the drugs could hugely improve their life expectancy and standard of living, he said.