An Air India flight was grounded shortly after landing in New Delhi after a fire broke out in its auxiliary power unit on Tuesday.

Passengers were disembarking flight AI315 from Hong Kong when the fire was detected, according to Airline.

"The incident occurred while passengers had begun disembarking and the APU was automatically shut down as per system design," an Air India spokesperson said.

The APU is installed at the back of the aircraft and serves as a backup power source, usually used to start the main engines and operate critical onboard systems while the aircraft is on the ground.

Passengers exited the aircraft safely but the aircraft, which landed at 12.31pm local time, was damaged, the spokesperson said.