NEW DELHI, Dec 19: Riot police fired water cannon on Wednesday at a protest in New Delhi over the gang-rape of a 23-year-old student who was left fighting for her life as outrage against the brutal attack grew across India.

Indian Prime Minister Manmohan Singh joined his ruling Congress party chief Sonia Gandhi in condemning Sunday night's “heinous” assault by six drunken man who were joyriding on a bus when they picked up the woman and a male companion.

After taking turns to rape the woman, the attackers then threw the pair off the vehicle.

Four people, including the bus driver, have so far been arrested, while a hunt is ongoing for two other suspects.

As the government tried to address the anger with series of steps, protests spread to other major cities including Mumbai, Kolkata and Ahmedabad.

Police used water cannon on one group of demonstrators as they tried to tear down steel barricades outside the official residence of Delhi’s Chief Minister Sheila Dikshit.

Before the violence broke out, protesters carrying banners chanted: “We want equal rights for women.”

“Women don't feel safe in the city, this is appalling,” said 18-year-old student protester Jayesha Koushik.

“The blame is always put on the women. ‘She was not wearing the right dress, she was out at the wrong time, she must have provoked it’. How can you blame the women for rape?”

“Rapes are happening to teach women a lesson,” said Kavita Krishnan of the All India Progressive Women’s Association who was among the protesters.

Even Bollywood superstar Amitabh Bachchan weighed in by calling on his Facebook page for “every Indian (to) become a vigilante, a soldier, a commander” to “fight such heinous crimes with strength and conviction”.

National crime records show that 228,650 of the total 256,329 violent crimes recorded last year were aimed against women.

Rape cases in India more than doubled between 1990 and 2008. Sunday night’s case was the latest in a series of particularly brutal attacks in the capital.—AFP