An Indian court awarded a life sentence on Monday to a police volunteer convicted of the rape and murder of a junior doctor at the hospital where she worked in the eastern city of Kolkata, rejecting demands for the death penalty and saying it was not a rare crime.

The decision to challenge the trial court’s sentence of life imprisonment came hours after the central agency opposed a similar plea by the state government.

An Indian court on Monday sentenced a police volunteer to life imprisonment for the rape and murder of an on-duty doctor last year – a crime that sparked nationwide protests. Sanjay Roy, 33, plans to appeal the judgment in a higher court.

The CBI is likely to file the appeal against the Sealdah court order by Friday with detailed arguments in favour of capital punishment, they said.

India's West Bengal state launched an appeal on Tuesday to overturn a life sentence in favour of the death penalty for a police volunteer convicted of the rape and murder of a junior doctor, a senior lawyer aware of the development said.

The Central Bureau of Investigation (CBI) will file an appeal before the Calcutta High Court (HC), seeking death sentence for Sanjoy Roy, who was sentenced to "life imprisonment until death" by a Sealdah court in the Kolkata rape-murder case,

Sanjay Roy was held guilty under Sections 66 (rape), 64 (causing injury resulting in death) and 103 (1) (murder) of the Bharatiya Nyaya Sanhita.

More individuals should have been questioned in the case while working conditions in India’s hospitals remain abysmal, analysts say.

The Bengal government has moved a division bench to file an appeal for the death penalty for the convict, Sanjay Roy, in the RG Kar rape-murder case.