A man has been knocked out in an altercation at a London railway station after an argument about the use of face masks.
Officers are reportedly investigating after the man was knocked to the floor by a passer-by at Clapham junction.
At the time the man and a friend had been arguing with South Western Railway staff after having seen another employee not wearing a face mask.
Coverings are currently compulsory on public transport for all those without a medical exemption to limit the spread of the coronavirus.
In footage capturing the moment, the victim can be heard saying “you’re not wearing one either” as a child and an unmasked man pushing a buggy walk past them.
In response to the comment, which the victim said was not aimed at the man, the passer-by turned – leaving the pram and child while shouting “don't f****** start on me”.
Footage then appears to show the other man punching him, knocking him to the floor unconscious and bleeding.
Speaking to PA news agency the victim said: "My friend asked one of the station staff a totally reasonable and polite question 'are you exempt from wearing a mask'.
"She'd snapped back saying 'none of your business'. Admittedly I lost my temper a bit.
He added he had "No idea" who the passer-by was, describing him as "just some random person who was walking without a face covering".
South Western Railway said the member of staff who was not wearing a mask had a medical exemption, adding that the assault was an altercation between members of the public and staff had assisted with first aid and alerted the police.
A spokesperson for South Western Railway, said: "Our staff reported this incident to the British Transport Police who are now investigating this.
"We will cooperate in this investigation fully, but as it is ongoing it would be inappropriate for us to comment further."
The British Transport Police are yet to comment on the incident.
Additional reporting by agencies.