Police are investigating claims that a man put a child into an armlock for refusing to take his feet off the seats on a train.

Images were posted online appearing to show a man wrenching a boy’s arm behind his back on a train. Witnesses reportedly said the incident followed a confrontation in which the man threatened to give three children a “clip round the ear”.

Witnesses told the Manchester Evening News that the three children, aged between about eight and 11, got on the train running from Clitheroe, in Lancashire, to Manchester at Blackburn and put their feet up on the seats.

British Transport Police are investigating https://t.co/KvQ7Qpmhml — Manchester News MEN (@MENnewsdesk) July 24, 2016

The man, who was believed to be in his 70s, told them off and they were “being quite cocky”, according to a witness who spoke to the paper, who did not want to be named.

The 17-year-old student said: “[The man] threatened them with a ‘clip around the ear’ and then went and sat back down. The children then put their feet back up and wouldn’t take them down. The guy then went over again and tried to take their feet down.”

The man, who has not been identified, is accused of assaulting one of the children at that point. A picture taken of the incident by another of the children has been circulating online.

Another witness told the paper the children had been “badly behaved” and were unaccompanied but said the man “acted like [a] US cop” and left the child in tears.

British Transport police tweeted that it was looking into the reports.