An Indian court has upheld the death sentence for four men convicted of raping and killing a medical student in New Delhi in December 2012.

The Delhi High Court on Thursday upheld the order to hang the four men handed down in their trial last September.

Mukhesh, Vinay Sharma, Pawan and Akshay Thakur were found guilty of the rape and murder of the student in a moving bus that shook the nation and triggered unprecedented street protests. The girl was brutally assaulted and then thrown off the bus.

Her friend, with whom she had gone to watch a movie and was with her in the bus, was also beaten up by the men.

Another accused, bus driver Ram Singh, died in Delhi's Tihar Jail in an apparent suicide.

A sixth member of the group, who was a minor at the time of the crime, was tried under laws for juveniles and sentenced to three years in a reformatory.

The gangrape and murder sent shockwaves across the nation. It prompted the federal government to enact stricter laws against sex crimes.