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.

An Indian court awarded the 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. The woman's body was found in a classroom at the state-run R G Kar Medical College and Hospital on Aug.

The police had sought the death penalty in a horrific but familiar crime. Its handling by the local authorities had outraged the nation.