A leading group of doctors in India is downplaying a Canadian-led study that found 500,000 female fetuses were aborted every year in India over the past 20 years.

The Indian Medical Association agreed there were incidences of sex selection in favour of boys, but said the practice has been greatly reduced since it was outlawed in 1994.

"This has not been happening for the past four or five years after strict laws were put in place," said Dr Narendra Saini, an association spokesperson.

The study was done by Prabhat Jha of St. Michael's Hospital at the University of Toronto and Rajesh Kumar of the Postgraduate Institute of Medical Research in Chandigarh, India. The results were published Monday in the Lancet, a British medical journal.

The study also found 933 girls were born for every 1,000 male babies in 2001.

In 1994, India banned the use of technology to determine the sex of fetuses and abortion on the basis of gender.

However, groups fighting against sex selection agreed with the study's findings, saying many of India's fertility clinics continue to offer the service discreetly. They said gender selection is a multibillion-dollar business that has gone underground.

Ranjana Kumari of the Centre for Social Research said India's government has been lax in enforcing the law.

"Not even one person has been booked so far. That shows how lax the system is," Kumari told the Associated Press.

"There is connivance between the doctors and the parents who don't want girl children. The government has to come forward on a war footing to put an end to this practice."