By Narayan Bareth BBC News, Jaipur

Female babies are not wanted in parts of India

Police in the Indian state of Rajasthan have launched an investigation into 21 doctors who are alleged to have been involved in aborting female foetuses.

The move came as women's groups marched in the state capital, Jaipur, in protest over the issue.

The claims came to light last month, when a private TV channel reported on female foeticides across Rajasthan.

The state health minister said those found guilty of such practices would be severely punished.

"The guilty would not be spared and I have asked all the district officials to monitor if any sex-determination tests are being carried out in their area," Mr Singh told the BBC.

'Falsely implicated'

Police have now filed cases under the Pre-Natal Diagnostic Techniques Act (PNDT), which makes selective abortions illegal, against 21 doctors from government-run and private hospitals.

Under Indian law, ultrasound tests on a pregnant woman to determine the gender of the foetus are illegal.

The doctors facing the investigation have rejected the charge, saying they have been falsely implicated.

The government move has also failed to satisfy civil rights groups who have demanded an investigation by the Central Bureau of Investigation (CBI).

"The police case is just an eye wash to delay the investigation. We don't have faith in the state agency. We want the CBI to investigate the scandal," Kavita Srivastva of the People's Union for Civil Liberties (PUCL) said.

Meanwhile angry women activists marched in Jaipur to highlight the declining sex ratio of women to men in the state.

The number of women in India has sharply declined

According to the last census, Rajasthan has 922 females per 1,000 males. However, some districts have an even more dismal sex ratio.

Women's groups say the government has failed to implement the PNDT Act and the female population is in decline

In a rare case in March, a doctor in Haryana state and his assistant were sentenced to two years in jail for revealing the sex of a female foetus and then agreeing to abort it.

According to one report, 10 million female foetuses may have been aborted in India over the past 20 years.