Doctors in India have begun a national strike, escalating the protest against the rape and murder of a female colleague in the West Bengal city of Kolkata.

The Indian Medical Association (IMA), the country's largest grouping of doctors, said all non-essential hospital services would be shut down across the country on Saturday.

The IMA described last week's killing as a "crime of barbaric scale due to the lack of safe spaces for women" and asked for the country's support in its "struggle for justice".

Protests against the attack and calling for the better protection of women have intensified in recent days after a mob vandalised the hospital where it happened.

In a statement, the IMA said emergency and casualty services would continue to run and that the strike would last for 24 hours.

Doctors at some government hospitals announced earlier this week that they were indefinitely halting elective procedures.

The IMA also issued a list of demands including the strengthening of the law to better protect medical staff against violence, increasing the level of security at hospitals and the creation of safe spaces for rest.

It called for a "meticulous and professional investigation" into the killing and the prosecution of those involved in vandalising, as well as compensation for the woman's family.

The rape of the 31-year-old female trainee doctor has shocked the country.

Her half-naked body bearing extensive injuries was discovered in a seminar hall at R G Kar Medical College last week after she was reported to have gone there to rest during her shift.

A volunteer who worked at the hospital has been arrested in connection with the crime.

The case has been transferred from local police to India's Central Bureau of Investigation (CBI) following criticism at the lack of progress.

More incidents of rape have made headlines in India since the woman's death and Prime Minister Narendra Modi has said that "monstrous behaviour against women should be severely and quickly punished".

Demonstrators are also calling for greater security at hospital and for better laws to protect medical staff

The woman's rape and killing has sparked a political blame game in West Bengal, with the opposition Bharatiya Janata Party (BJP) accusing the governing Trinamool Congress Party (TMC) of orchestrating the attack.

The TMC has refuted the allegation and has blamed "political outsiders" for stoking the violence.

Tens of thousands of women across West Bengal participated in the Reclaim the Night march on Wednesday night to demand "independence to live in freedom and without fear".

Though the protests were largely peaceful, clashes erupted between the police and a small group of unidentified men who barged into the RG Kar Hospital - the site of the crime - and ransacked its emergency ward.

At least 25 people have been arrested in connection with the incident so far.

Protests have also been held in many other Indian cities like Delhi, Hyderabad, Mumbai and Pune.

"It feels like hope is being reignited," one demonstrator, Sumita Datta, told the AFP news agency as thousands of people marched through the streets of Kolkata on Friday.