The potentially lethal condition is the leading cause of liver disease in Western Europe and the most common reason for liver transplants.

Scottish biotechnology company Viragen, based in Penicuik, near Edinburgh, has received the go ahead for tests on human subjects with Omniferon.

Hepatitis C can prove fatal

The company, which is a subsidiary of a firm based in Florida, said Scottish patients would be among the first to benefit from the new drug through involvement with the Scottish National Blood Transfusion Service.

It anticipates Omniferon could be available in three years.

Up to 350,000 British citizens and 170m worldwide are affected by the disease, which currently has no vaccine and no cure.

The hepatitis C virus can remain in the bloodstream for 20 years unknown to the carrier and can cause liver failure if untreated.

A company spokesman said: "Some experts believe that the risk of hepatitis C infection is even greater than that of HIV, and with an estimated 35,000 cases in Scotland alone, the risks are increasing by the day."

Medical workers

Those particularly at risk include drug-users, medical workers, organ transplant patients and people in the developing world.

The new drug, produced from human white blood cells, comes from developing a way of producing naturally-derived interferon, an anti-infection protein.

At present, said the company, the world market for hepatitis C treatment is dominated by synthetic interferons which can cause serious side effects.

Dr Magnus Nicolson, managing director of the firm's Scottish operation, said the company had always believed natural interferon has big potential and other companies had been deterred by its high manufacturing costs.

Cost effective

"Therefore our goal was to make natural interferon cost effective," he said.

"Viragen's research efforts focused on process development. As a result, we have had to solve many process-related issues at a much earlier stage in the development process than is typical.