Dirty equipment used at a hospital could have exposed nearly 200 patients to infectious disease.

An investigation has been launched into the incident at the Freeman Hospital, in Newcastle, and at-risk patients are to be called in for testing.

The equipment was a bronchoscope, a flexible tube used to help diagnose respiratory conditions such as pneumonia and lung cancer.

Records show it was used on 172 patients in the hospital's critical care unit.

Hospital bosses are taking advice from the Health Protection Agency (HPA) on whether or not they need to call in patients who could have been exposed to blood-borne viruses such as hepatitis, vCJD and HIV.

The blunder was picked up after a similar incident in Northern Ireland led to a large numbers of patients being recalled for screening.

In response to the incident, the Government's Medicines and Healthcare Products Regulatory Agency (MHRA) ordered all NHS trusts to review their cleaning processes in June

Katherine Murphy, of the Patients' Association, said: "The safety of patients should always be paramount and corners should not be cut over cleaning and sterilisation.

"Even if this risk is low, the hospital owes it to the people they are looking after to make sure that they are treated correctly and do not have their lives put at risk by using contaminated equipment."

A report by Newcastle Hospitals Trust said its survey of cleaning procedures showed that most decontamination processes met requirements.

But it noted: "A specific problem was highlighted with an inadequate cleaning process for one bronchoscope in critical care at the Freeman Hospital.

"The actual risk is felt to be low, although further work is ongoing to identify the patients, and the alert from the MHRA stipulates that the trust should take advice from the HPA on whether the 'look-back' exercise is warranted and on the form this should take.