The Indian government yesterday signalled that it would be imposing tougher sentences on doctors who illegally abort female foetuses - a tacit admission that the law was not working.

Experts estimate India has lost 10 million girls in the past 20 years. Yet in the 14 years since selective abortion was outlawed only two doctors has been convicted of the crime - and officials admit one of those is back in business.

The reason, says the government, is that under the existing act doctors are only suspended, face a fine of 50,000 rupees (£625) and a jail term of three months. Instead the health minister wants doctors conducting illegal sex determination tests to be struck off permanently, face a fine of 700,000 rupees (£8,750) and imprisonment for up to three years.

Manmohan Singh, the Indian prime minister, will issue a call next week to clamp down on female foeticide. This comes after a campaign by the women and child development ministry to convince parents to give up girls for adoption rather than aborting them. The idea appears to have been quietly abandoned after running into bureaucratic quicksand.

Indian parents are choosing to abort female foetuses in such large numbers that 900,000 girls are now being lost every year.

Campaigners said that the problem was not the penalties but the implementation of the present act. Sabu George, a Delhi-based researcher who works on female foeticide, said: "Hundreds of thousands of sex selective abortions happen every year, yet only a few hundred doctors are caught. Conviction rates are ridiculously low. But the real problem is getting state police to catch these criminal doctors."

The latest estimate of India's sex ratio at birth (SRB) comes from a sample registration system that covers 1.3m households. For the two years up to 2004 India had 882 girls to each 1,000 boys.

George says that a preference for boys, who carry on the family bloodline and inherit wealth, has always existed in Indian society.

But more people can now afford the medical technology which makes it possible to tell the sex of a baby while it is still in the womb.

Richer parts of India are worst affected - with parents sometimes ordering online home-kits which claim to determine the sex of a baby in the womb. In wealthy Haryana there are now just 770 girls being born for every 1,000 boys.