Experts report a decline in sexual desire among stressed-out males, though loss of libido is believed to affect more than a third of women and up to one in six men.

Scientists led by Professor Robert Millar, at Britain's Medical Research Council's Human Reproductive Sciences Unit in Edinburgh, initially thought the drug would work only on women - but now believe it could also be effective on men.

"This drug would cut out the need for Viagra completely - Viagra does not produce desire, it simply leads to an erection but not to the desire for sex," said Professor Millar.

"This drug would arouse and produce the desire for sex at the same time, in both men and women," he was quoted as saying by the Daily Mail of Britain on Monday.

Apart form heightening sex drive in both men and women who struggle with their libido, the drug is believed to have the side-effect of encouraging weight-loss and could have the potential to boost fertility rates, the report said.

After tests on animals have proved successful, researchers in Edinburgh are now working on an equivalent for humans, it said. Professor Millar said when female musk shrews and marmoset monkeys received injections in laboratory tests, they demonstrated classic mating behaviour towards their male counterparts.