A senior Indian policeman has provoked fury after advising women to avoid rape by not travelling after dark and carrying chilli powder to throw at potential attackers.

The comments by KP Raghuvanshi, commissioner of police in Thane, a satellite city of Mumbai, come amid widespread anger following the gang rape of a 23-year-old student in Delhi on Sunday.

Ranjana Kumari, one of India's best known women's rights activists and director of the Centre for Social Research in Delhi, was scornful of Raghuvanshi's suggestion.

"This is just a sexist sort of solution. They want women to stay at home. And how is chilli powder going to help against six or seven men?" she said.

Kajol Batra, a 28-year-old student in the capital, called the suggestion idiotic. "We should not be scared of going out and we shouldn't have to protect ourselves with cooking ingredients," she said.

Demonstrations triggered by the attack in Delhi continued across India on Thursday with protesters, mostly students, blocking a national highway in the northern state of Jammu and Kashmir to demand a death sentence for the six men accused of the attack, and vigils in other major cities. The victim remains critically ill.

It has emerged that she and her male friend lay at the roadside where they had been dumped, naked and bloodied, for nearly an hour before police arrived. About 50 people gathered around them, officials later said, but no one offered any help. Police eventually had to fetch sheets from a nearby hotel to cover them.

The debate in India on prevention of such attacks has largely focused on harsher punishments, more police resources and better monitoring of public transport.

Kumari suggested creating a sexual offenders register that the public could consult. "Convicted attackers would not get jobs, or be able to rent homes, or buy property. The social ostracism would be a very big deterrent," she said.

The intense media interest in the attack – TV journalists outside the hospital where the victim is being treated file updates on her condition hourly – has led to the reporting of other attacks which would usually never make headlines.

The body of a 10-year-old girl, who police believe had been gang-raped before she was killed, was retrieved from a canal in the poor northern state of Bihar on Wednesday. Also in Bihar, a 14-year-old schoolgirl was in critical condition after she was raped by four men. In north-east India, police are investigating the apparent abduction and rape of a 24-year-old woman near the city of Bagdogra by a neighbour and friends.

Commentators have blamed such incidents on a variety of factors, ranging from rapidly evolving roles in a fast-changing economy, to a macho culture, particularly in the north of the country, which encourages men to believe that rape is something to be proud of. Placards held by some protesters this week read "Real Men Don't Rape".