The 'superbug' can live inside E.coli (above) and trigger further infections

Scientists are warning the bug, an enzyme called New Delhi-Metallo-1 (NDM-1), could spread across the world as nothing is being developed to treat it.

There has been 37 reported cases in the UK, mainly among patients who travelled to areas of Asia for cosmetic surgery, transplants and cancer treatment.

The bug can exist inside different bacteria, like E.coli, and cause infections in other parts of the body.

It can also move from one bacterium to another and experts are concerned it may attach itself to more dangerous diseases and cause them to become resistant to antibiotics.

The scientists, writing in the journal Lancet Infectious Diseases, said: "It has an alarming potential to spread and diversify."

Dr David Livermore, one of the researchers and who works for the UK's Health Protection Agency (HPA), said: "The NDM-1 problem is likely to get progressively worse in the foreseeable future.

"The potential for wider international spread and for NDM-1 to become endemic worldwide are clear and frightening."

Infections have already been passed from patient to patient in UK hospitals.

Researchers say the way to stop NDM-1 is to identify and isolate any patients who are infected.

A Department of Health spokesman said: "We are working with the Health Protection Agency on this issue.

"The HPA alerted the NHS in January and July last year to be vigilant about these bacteria and take appropriate action where necessary.

"Hospitals need to ensure they continue to provide good infection control to prevent any spread, consider whether patients have recently been treated abroad and send samples to HPA for testing.

"The HPA is continuing to monitor the situation and we are investigating ways of encouraging the development of new antibiotics with our European colleagues."