Scientists have expressed concern about a new superbug, which has developed near total resistance to antibiotics.

The presence of the superbug was discovered in the UK, India, Pakistan and Bangladesh.

Researchers believe the spread of the bug has been aided by so called 'medical tourism', whereby patients travel abroad for elective surgery.

A new gene called New Delhi metallo-beta-lactamase, or NDM-1, was found in patients in South Asia and in Britain by researchers.

NDM-1 makes bacteria highly resistant to almost all antibiotics, including the most powerful class called carbapenems, and experts say there are no new drugs on the horizon to tackle it.

'At a global level, this is a real concern', Timothy Walsh from Britain's Cardiff University said.

'Because of medical tourism and international travel in general, resistance to these types of bacteria has the potential to spread around the world very, very quickly. And there is nothing in the (drug development) pipeline to tackle it.'

Almost as soon as the first antibiotic, penicillin, was introduced in the 1940s, bacteria began to develop resistance to its effects, prompting researchers to develop many new generations of antibiotics.

But their overuse and misuse have helped fuel the rise of drug-resistant superbug infections like methicillin-resistant Staphylococcus aureus (MRSA).

In a study published in The Lancet Infectious Diseases journal today, Mr Walsh's team found that NDM-1 is becoming more common.

'India also provides cosmetic surgery for other Europeans and Americans, and it is likely NDM-1 will spread worldwide', the scientists wrote in the study.

Mr Walsh and his international team collected bacteria samples from hospital patients in two places in India, Chennai and Haryana, and from patients referred to Britain's national reference laboratory between 2007 and 2009.

They found 44 NDM-1-positive bacteria in Chennai, 26 in Haryana, 37 in Britain, and 73 in other sites in Bangladesh, India, and Pakistan.

Several of the British NDM-1 positive patients had recently travelled to India or Pakistan for hospital treatment, including cosmetic surgery, they said.

Experts commenting on Mr Walsh's findings said it was important to be alert to the new bug and start screening for it early.

'If this emerging public health threat is ignored, sooner or later the medical community could be confronted with carbapenem-resistant (bacteria) that cause common infections, resulting in treatment failures with substantial increases in health-care costs', Johann Pitout from the University of Calgary in Canada wrote in a commentary in same journal.