NEW DELHI (AFP) - Indian Prime Minister Manmohan Singh on Sunday underlined the need for more action to tackle crime against women as the country reels under a spate of sex attacks that have made global headlines.

Dr Singh said his government had moved quickly to bring about significant amendments in the criminal law dealing with sexual offences against women following the December gang-rape of a 23-year-old student in New Delhi.

"But, notwithstanding the steps that have already been taken, a great deal more needs to be done as far as offences against women are concerned," he said at a conference of chief ministers and chief justices in Delhi.

Attacks on women in India have been in the spotlight since December 16, when the student was brutally attacked and raped by six men on a moving bus in the capital. She died two weeks later of her injuries.

The case triggered outrage at home and abroad, prompting parliament to toughen laws to make the country safer for women.

The new law was passed the same day that a British tourist jumped off her hotel balcony in the Taj Mahal city of Agra in a bid to escape an alleged sex attack.

That incident came just days after a Swiss cyclist was gang-raped in Madhya Pradesh state in a brutal assault commentators said underscored risks women face in the country of 1.2 billion people.

Last week, four sisters walking home in northern Uttar Pradesh state suffered severe burns after being attacked with acid by two men on a motorbike.

Dr Singh said the need for speedy and affordable justice had come into sharper focus in the wake of the growing crimes against women.

"Presently, over three crore (30 million) cases are pending in various courts across the country and 26 percent of them are over five years old," Dr Singh said, urging speedy trials to reduce the backlog.