A man who headbutted an unruly passenger on board a packed train has been identified as an off-duty police officer.

Dramatic footage shows two men involved in a dispute, with the shorter, bearded man aggressively shouting at the other on a train leaving London.

The other man, the off-duty police officer, restrains the shorter man with his hands, then approaches him and delivers a stooping headbutt that sends him falling to the floor.

Several passengers on the train gasp following the contact before others laugh and even cheer.

Police confirmed to Metro that the man was an employee of the Metropolitan Police and the footage of the incident had been reviewed.

A Metropolitan Police Service badge.

A spokesperson said no further action would be taken against the officer.

“The Met’s Directorate of Professional Standards have reviewed the video and the details surrounding the incident and are satisfied that there is no indication that the officer committed a criminal offence, nor that he behaved in a manner that would justify disciplinary proceedings,” the spokesperson said.

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Further footage shows the suited man restraining the man on a platform with two others as he was placed in handcuffs.

The British Transport Police said they had received a report of a man making violent threats on board a train on Thursday.

The man was later arrested at an Upminster station where he was arrested on suspicion of carrying a knife and theft by finding.

It is believed his grievance initially began over seating.

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