London (PTI): Men often crib that most women like to play hard to get. Now, researchers claim to have found the possible reason -- it raises a female's chances of finding a "good" mate.

A new study, published in the Journal of Theoretical Biology, has revealed that women who prolong mating courtship and refuse to have sex with a male partner on their first date can end up in making a successful match. Lead researcher professor Robert Seymour of University College London said: "Longer courtship is a way for the female to acquire information about the male.

"By delaying mating, the female is able to reduce the chance that she will mate with a bad male. A male's willingness to court for a long time is a signal that he is likely to be a good male.

"Long courtship is a price paid for increasing the chance that mating, if it occurs, will be a harmonious match which benefits both sexes. This helps to explain the commonly held belief that a woman is best advised not to sleep with a man on a first date."

In fact, the researchers have based their findings on an analysis of a mathematical model, which showed that "more reliable men were willing to wait longer before having sex for the first time", The Daily Telegraph reported. On the contrary, less suitable men were not as likely to continue dating, the study found.

However, co-researcher Peter Sozou of Warwick Medical School has warned the strategy was not foolproof. "The problem the female faces is how to screen out bad males, and this is where long courtship comes into play. "A male is assumed to always want to mate with a female, but a good male is more willing to pay the cost of a long courtship in order to claim the prize of mating.

"The female's strategy is a compromise -- a trade-off between on the one hand the greater risk of mating with a bad male if she mates too quickly, and on the other hand the time cost of delay.

"Under this compromise there remains some risk she will mate with the wrong type of male. She can't eliminate this risk completely unless she decides never to mate."