It's a very important moral argument to the government to answer our calls to help people who have been infected with Hepatitis C

Haemophilia Society spokesman

Lawyers for the claimants hailed the judgement as a "landmark decision".

It is the first multi-party action to go to court under the Consumer Protection Act 1987.

Anthony Mallen, of Deas Mallen solicitors, Newcastle-upon-Tyne, praised the act and the EU directive on which it is based for strengthening consumer laws.

"Producers are not liable for risks which are genuinely unknown to exist, but as soon as the possibly dangerous nature of the product has been discovered by someone somewhere, they will be liable if they continue to supply dangerous products.

The claims were brought against the National Blood Authority, in England and the Velindre NHS Trust in Wales who contested the action.

The organisations who will be affected by the ruling are the NHS bodies today answerable for the production and supply of blood and blood products by the National Blood Transfusion Service since March 1, 1988.

During the case, Michael Brooke QC, for the defendants, said: "All of these claimants have suffered in one way or another the stigma of being Hepatitis C sufferers.

"The public is often confused about HCV and wrongly believes that it is similar to HIV infection."

The case is important because it sets an important precedent by establishing a legal link between medical liability and consumer rights.

A second case, involving nine claimants including haemophiliacs and a woman infected during a heart transplant, will have a preliminary hearing in May.