Hospital specialists criticised the Government yesterday for failing to act to curb the spread of hepatitis C, a lethal blood-borne virus.

The silent epidemic of hepatitis C is officially estimated to have infected 200,000 people in the UK - four times as many as HIV - and more than 100 people are being infected each week.

It is already the main reason for liver transplants and is predicted to be killing more people than Aids by 2020, yet only a quarter of victims know they are infected and just 1 per cent are receiving treatment.

The seriousness of the threat was recognised by the Department of Health when it published a strategy for dealing with the epidemic 18 months ago and promised an action plan by the end of 2002. But a year later nothing has been done.

Graham Foster, professor of hepatology at the Royal London Hospital, said: "There is much disappointment at the lack of an action plan. Absolutely nothing is happening."

A new study, to be published shortly, will show a dramatic increase in the number of new infections, Professor Foster said. Last month, the Health Protection Agency revealed that 5,901 cases of hepatitis C infection were diagnosed in 2002, compared with fewer than 1,000 in 1994.

"The figures are horrifying. Over the next 10 to 15 years liver disease and cancer rates will soar. The Government is talking the talk but it is doing nothing else," Professor Foster said.

The outlook for sufferers has been transformed in the past decade as new drug cocktails have increased the proportion of patients who can be cured to 60 per cent. Other countries have established programmes to identify and treat patients. France treats 15,000 patients a year compared with 2,000 a year in Britain.

"In the UK we are just discussing it and hoping it will go away," Professor Foster said.

Most victims are unaware they are infected, but up to 30 per cent will suffer severe symptoms caused by chronic inflammation of the liver including cirrhosis, liver cancer and death over two to three decades.

William Irving, professor of virology at Nottingham University, said Britain was one of the few countries with a policy on hepatitis C.

"But it is disappointing we haven't seen an implementation plan or any funding for an implementation plan. There are a lot of people out there with hepatitis C and there is a window of opportunity to treat them now before they develop liver disease."

One reason for neglect of the disease is thought to be its "low-life" association with intravenous drug use - it is spread by shared needles.

But increasingly it is also being spread by "social" drug use such as snorting cocaine. Straws used to snort cocaine are often passed around and may become contaminated by blood from the nasal epithelium caused by the corrosive, alkaline nature of the drug.

The virus can also be spread through sex, though this is rare, and through skin piercing, tattooing and shared use of razor blades and toothbrushes. It is 10 times more infectious via blood-to-blood contact than HIV, but less infectious than HIV via sexual contact.

Many victims became infected through experimenting with injecting drugs decades ago and now lead stable lives with families and jobs. Others were infected through blood transfusions.

The virus was identified in 1989 but screening of blood was not introduced until 1991, and many sufferers do not know how they became infected.

Charles Gore, chief executive of the Hepatitis C Trust, said: "There was a lot of experimentation with intravenous drug use at the end of the Seventies and early Eighties - far more than most people think. There was a huge influx of heroin after the Iranian revolution in 1979 and experimentation involves someone showing you how to do it and using their syringe. Now those people are starting to come through with chronic liver disease.

"The Government is dragging its feet on this - there is a lack of political will and a fear of the cost implications."

A treatment based on interferon can eliminate hepatitis C from the body, and a new slow-release version was recommended by the National Institute for Clinical Excellence last month. But the virus is symptomless in its early stages, meaning efforts have to be made to test and identify those infected. There is also a shortage of trained nurses able to give the treatment which lasts up to a year.

A spokeswoman for the health department said: "The hepatitis C action plan will be published in due course."