A woman is in critical condition after a man poured petrol on her and set her on fire on a tram in Germany.

A man poured a liquid - believed to have been gasoline - over a woman on a tram in eastern Germany on Sunday and set her on fire, police said.

The woman was taken to the hospital with life-threatening injuries, while the attacker fled, foreign media wrote, according to Telegraph.

Police said no other people were injured in the incident in the eastern city of Gera.

Passengers stopped the tram by pressing an emergency button and the attacker took the opportunity to escape by opening the doors.

The tram driver immediately extinguished the flames with a fire extinguisher and the 46-year-old woman was taken to the hospital by helicopter.

Police later said they were looking for the victim's husband, also 46 years old.

They appealed to anyone who sees him or knows his whereabouts to inform them immediately and said they could not currently rule out the possibility that he posed a danger to the public.

There was no immediate word on a possible motive for the attack, or what exactly the liquid used was.Telegraph/