A total of 75 patients from all parts of the country have been identified with the bug, called Type 027, which produces 10 times more toxin than existing strains and is causing severe illness and deaths.

Two hospitals hit by outbreaks – Stoke Mandeville and the Royal Devon and Exeter – have had hundreds of cases and more than 30 deaths.

Patricia Hewitt, the Secretary of State for Health, announced an independent inquiry into the outbreak at Stoke Mandeville after it was revealed by The Independent on 6 June. Until then, the type 027 strain was almost unheard of in the NHS. Only two isolated cases had been identified, at Preston in January 1999 and Birmingham in April 2002.

Since the outbreak at Stoke Mandeville, 13 further hospitals have been identified with the infection, covering all parts of the country including the North, the Midlands, the South-east and the South-west. The details were released by the health department in a written answer to David Lidington, Conservative MP for Aylesbury, which includes Stoke Mandeville.

Jane Kennedy, the Health minister responsible for hospital infections, said: "Cases of C.difficile 027 have occurred in Preston, Birmingham, Winchester, Bristol, Romford, Southampton, Truro, Carshalton, High Wycombe, South Tyneside, Newcastle, South Tees, Sunderland, Stoke Mandeville and Exeter. As of 16 June 2005, 75 isolates of C.difficile 027 had been received by the Anaerobe Reference Laboratory in Cardiff."

Mr Lidington said there were concerns about the capacity of the laboratory to handle the volume of referrals. "This is a problem for the country," he said. "It is important that the inquiry announced by Patricia Hewitt looks far wider than Stoke Mandeville. It needs to be sufficiently independent to look at the Department of Health's role and to ask whether the department was slow off the mark and whether it has done all that needs to be done."

Jon Brazier, director of the laboratory, said more hospitals may be infected by the new strain but were unaware of its presence. C.difficile forms spores which are hard to remove with normal cleaning but the Type 027 strain is more difficult to eradicate as well as being more toxic.

"What worries me is that we only have a snapshot of the situation in hospitals that have sent us samples," he said. "As more hospitals send samples we hope to get the true picture nationally. It is an unfolding situation."

The Department of Health introduced mandatory reporting for C.difficile in 2004 but systematic sampling of cases to identify the strain of infection is still being rolled out.

A spokesman for the health department said: "We are keeping a close eye on this developing situation. We are offering advice to trusts on putting the correct infection control measures in place. The terms of the inquiry into the Stoke Mandeville outbreak are still to be decided with the Healthcare Commission."

C.difficile affects mainly vulnerable elderly patients and causes severe diarrhoea. It can be treated with antibiotics but one in five cases is resistant and some patients develop pseudo-membranous colitis, a life -threatening condition.

Type 027 is similar to a strain that caused outbreaks in Quebec and the US.