Thousands of protesters clashed in India's eastern city of Kolkata on Wednesday, where demonstrations seeking justice for a murdered doctor spiralled into violent street skirmishes between political rivals.

The discovery of the 31-year-old doctor's bloodied body at a state-run hospital in Kolkata on August 9 stoked nationwide anger at the chronic issue of violence against women.

That sparked strikes by medics and rallies backed by thousands of ordinary citizens across India, although many doctors have since returned to work.

But repeated protests in West Bengal state capital Kolkata have transformed into clashes between the state's ruling All India Trinamool Congress (AITMC) and the opposition Bharatiya Janata Party (BJP).

The Hindu-nationalist BJP is the party of Prime Minister Narendra Modi and holds power nationally, but sits in opposition in West Bengal.

"We want justice", BJP supporters chanted, referring to the murdered doctor, then demanding the resignation of AITMC leader Mamata Banerjee, the chief minister.

"Go back! Go back!" AITMC supporters shouted in return.

Banerjee accused the BJP of "dirty politics" and exploiting the doctor's death, speaking at a rally of party loyalists.

On Tuesday, police clashed with protesters, firing tear gas canisters and water cannons, and arresting at least 245 people.

That prompted BJP supporters on Wednesday to launch a day-long shutdown of Kolkata, with skirmishes against AITMC supporters in the morning.

- 'Horrific' -

Protesters erected barricades to close roads and railway lines, with police reporting clashes between rival workers across the city and in adjoining districts.

Arjun Singh, a former BJP lawmaker, alleged his party loyalists were attacked by supporters of Banerjee's AITMC, and two people were injured.

AITMC "activists blocked the roads to prevent BJP supporters from marching", Singh told AFP.

"Train services were disrupted as protestors squatted on railway tracks," Kousik Mitra, a senior railways official told AFP.

Police later enforced an uneasy peace between them and their rivals.

Doctors, in a separate protest, are expected to hold a rally in memory of their murdered colleague later on Wednesday.

Banerjee also said she wanted to pass "anti-rape" laws to try and execute those guilty of sexual assault "within seven days of the crime", without giving further details.

One man has been detained for the murder, but West Bengal's government has faced public criticism for the handling of the investigation.

India's Supreme Court has ordered a national task force to examine how to bolster security for healthcare workers, saying the "horrific" killing had "shocked the conscience of the nation".

The gruesome nature of the attack has invoked comparisons with the horrific 2012 gang rape and murder of a young woman on a Delhi bus.

It became a major political issue, and was seen as one factor in the BJP's subsequent success in elections.

The attack also sparked widespread outrage in a country where sexual violence against women is endemic.

An average of nearly 90 rapes a day were reported in 2022 in the country of 1.4 billion people.