The drug mimics serotonin and a certain forms of dopamine which are substances produced naturally in the body connected with mood, reward, and learning.

Women taking 100 milligrams of flibanserin once a day reported greater numbers of "satisfactory sexual encounters", higher levels of sexual desire, and reduced stress associated with sexual problems.

Professor John Thorp, from the University of North Carolina at Chapel Hill, US, who led the research, said: "Flibanserin was a poor antidepressant.

"However, astute observers noted that it increased libido in laboratory animals and human subjects. So, we conducted multiple clinical trials and the women in our studies who took it for hypoactive sexual desire disorder reported significant improvements in sexual desire and satisfactory sexual experiences.

"It's essentially a Viagra-like drug for women in that diminished desire or libido is the most common feminine sexual problem, like erectile dysfunction is in men."

Viagra, which helps men overcome impotency, also began life with another purpose in mind. It was originally designed to treat angina, the chest pain associated with heart disease.

Scientists discovered that Viagra had the welcome side effect of helping the penis to fill with blood, thereby producing an erection.

Pooled results from three of four trials testing flibanserin's ability to boost women's sex drives were presented at the Congress of the European Society for Sexual Medicine in Lyon, France.

A total of 1,946 pre-menopausal women aged 18 and older were treated either with flibanserin or an inactive "dummy" placebo drug for 24 weeks.

Prof Thorp said the treatment could provide a new alternative for women without having to resort to hormones which can have side effects.