Two homeless men in Berlin have suffered severe burn injuries after an unknown individual doused them with a flammable liquid and set them on fire at a Berlin train station.

The men, aged 47 and 62, were taken to hospital after the attack, which occurred at the Schoeneweide train station in southeastern Berlin during the night between Sunday and Monday.

The men’s belongings were also set on fire.

Police declined on Monday to confirm reports by German newspapers Bild and Berliner Zeitung that passers-by came to the scene and put the fire out with a fire extinguisher retrieved from a nearby fast-food stand.

Burn marks remain at the Schoeneweide train station. Photo: DPA/AAP

The motive for the attack remained unclear, though authorities have launched an investigation on the suspicion of attempted murder.

The incident calls to mind another arson attack on a sleeping homeless man in Berlin in December 2016 that made headlines across Germany.

A group of young men tried to set the man on fire at the city’s Schoenleinstrasse train station on Christmas Eve, but passengers prevented the man from sustaining any injuries.

The main attacker was sentenced six months later to two years and nine months in prison.

Three accomplices each received eight months probation.

The few remaining possessions of the homeless duo are left at the station. Photo: DPA/AAP