A man was slashed in the face by a knifeman aboard a London Underground train.

The man was targeted in an unprovoked attack on a Metropolitan Line train in the early hours of Friday, February 12.

After threatening one man with a knife, the suspect, described as a black man, allegedly turned on another passenger as the train approached Northwood Hills, and slashed the side of his face.

The victim was taken to hospital, where he required five stitches to his face.

British Transport Police want to speak with the man captured in this CCTV image in connection with the attack.

PC Mike Hender said: “This was an unprovoked attack which left a victim with a nasty cut to his face and I am determined to find the man responsible.”

The suspect is described as a black, about 6ft tall, and aged between 30 and 40 years-old.

Anyone with information is asked to call BTP on 0800 40 50 40, quoting incident number 21 of 12/2/2010.