A huge increase in counterfeit drugs in the U.S. is posing a serious threat to public safety, especially in developing countries, medical journal The Lancet says.

Bogus drugs on the market are estimated to have jumped 800 per cent between 2000 and 2006.

The editorial, published in the May 10 issue, suggests phoney medications may account for around 10 to 30 per cent of medicines on the market in developing countries.

"Antimalarials have been a particular target for counterfeiters, and fakes have flooded the market in many Asian countries," the editorial said.

"The substances used to adulterate medicines can vary from chalk, to antibiotics, to highly lethal substances that cause alarming spikes in mortality rates."

Using sophisticated technology, criminals are producing and packaging convincing phoney drugs, the editorial said. By 2010, the counterfeit drug industry is projected to generate sales of $75 billion US, according to the Center for Medicine and the Public Interest.

The Lancet editorial also suggests counterfeiters may have played a part in the contamination of the recently recalled blood thinner drug heparin. The U.S. Food and Drug Administration last week told a Congressional hearing the drug may have been intentionally contaminated with oversulfated chondroitin sulphate.

"Why the stocks might have been intentionally contaminated is unclear, but the fact that oversulfated chondroitin sulphate is structurally similar to heparin but about 100 times cheaper, raises the very real possibility that it could have been added by counterfeiters."

Heparin has been recalled in the U.S., Canada, Germany, France and Japan.