They are trying to trace over 150 patients who may have been infected with the liver disease after undergoing antohaemotherapy treatment at the Finchley Alternative Medical Centre.

Barnet Health Authority is working with the Royal Free hospital and the Public Health Laboratory Service.

They have already traced patients dating back to last July, but are extending the search to January 1997 after a patient who visited the clinic early last year tested positive for hepatitis C during a blood test.

Hepatitis C is thought to be responsible for the majority of liver cancer cases in Europe.

Hepatitis B

So far, 28 patients are confirmed to have contracted hepatitis B at the clinic. Antohaemotherapy involves taking blood, mixing it with a saline solution and injecting it back into the body.

Stephen Farrow of Barnet Health Authority

The treatment is rare and is used on a range of ailments, including back pain and allergies. Barnet Health Authority says it has only been able to find two other clinics in the UK who offer the treatment.

The Finchley clinic has stopped doing acupuncture and antohaemotherapy since the outbreak was first identified in February and is co-operating with health officials.

Saline

A spokesman for Barnet Health Authority said experts believe the saline solution may have become infected with blood from a patient with hepatitis. The clinic used different needles on each patient, but drew saline from just one bottle.

It has been reported to the General Medical Council. As it is private, it is not required to have a licence and the health authority can take no action.

Health officials are having trouble tracing patients who have undergone the treatment since they may come from all over the country and some may have come from outside the UK.

They are offering testing for hepatitis B and C and follow-up help or treatment if a person is found to be infected.