Police are investigating after an NHS worker was kicked and left unconscious following a confrontation over face masks.

The victim, 63, was punched repeatedly to the floor and had his head stamped on five times while on the 149 bus near to Seven Sisters station on August 23.

The man who works for NHS track and trace, was attacked after pointing out that the suspect had a face mask beneath his chin.

He was stood by the middle doors of the bus, while the suspect boarded the bus at the next stop at around 9.45pm.

CCTV footage shows that around five minutes later, the suspect followed the victim towards the back doors, where the NHS worker had gone to try and put some distance between them – when without any warning the man launched into a violent physical attack.

Investigating officer PC Bowman, from the Roads and Transport Policing Command, said: “Although there is no sound on the CCTV and all the victim remembers is waking up in hospital, we believe that this was all triggered by face masks. We think that the attacker, who had his face covering beneath his chin, took offence when the victim, who was fully covered, consciously moved away from him.

“When the attacker then follows the victim to the back of the bus, he can be seen pointing and gesturing at the victim’s face mask before he starts repeatedly punching and kicking him. This was a totally unwarranted violent assault and we urgently need to speak to this man.

"If anyone knows who he is or has any other information – or witnessed this offence – please call.”

The suspect is described as a black man aged approximately 23-25 years, tall and with an athletic/muscular build. He was wearing blue tracksuit bottoms, a white vest and white trainers.

Anyone with information should call detectives on 07880 429 486 or 101 quoting ref CAD 7981/23Aug. Alternatively call Crimestoppers anonymously on 0800 555 111 or tweet @MetCC with any information.