The vice-chairman of the Chinese Medical Association, Cao Zeyi, said the figures were remarkable because Chinese women had traditionally considered sex a taboo subject.

Four years ago, a study by the Institute of Sociology at Beijing's Renmin University found that only 19.1 per cent of women were interested in sex.

But Professor Cao said Chinese women were still sexually subservient. On average they had sex six to seven times a month, compared with 10 to 15 times a month for American women.

The internet survey found that 2.5 per cent of respondents were lesbians and 3.7 per cent described themselves as bisexual.

'Many didn't tell the truth and are even afraid to acknowledge their orientation themselves,' said Professor Cao, who suspected that 8 to 10 per cent of Chinese women might be homosexual.

The survey also uncovered a high rate of sex outside marriage. Survey director Ma Xiaonian said 40.8 per cent of married women had admitted to cheating on their husbands.

Both Professor Cao and Mr Ma said they were surprised at the level of sexual knowledge among the women surveyed.

'They were good at answering questions about climaxes and sensitive points,' Mr Ma said.

But some experts expressed doubts about the validity of the survey's results.

Li Yinhe , of the Chinese Academy of Social Sciences, said internet questionnaires were unlikely to provide a good research sample because they mainly focused on people who frequented the internet.

Mr Ma said most of those surveyed came from large cities, with more than half aged between 26 and 39.

Professor Li said people were also more likely to provide false information in an internet survey.