An altercation broke out on a London-bound commuter train – in a dispute believed to be over elbow room.

The fracas aboard Tuesday's 5.30am Greater Anglia Service from Norwich to Liverpool Street via Ipswich, left one man with cuts to his face.

Another man was arrested on board by an off-duty officer who happened to be travelling on the train.

One passenger, who asked to remain anonymous, said he had never seen anything like it.

'Everybody was a bit shocked, the fight appeared to be over elbow room,' he said. 'The carriage wasn't even full at the time.'

It is believed the altercation, which took place in a standard class carriage, got out of hand as the train neared Chelmsford at about 6.50am.

The two men had been sitting together in the centre of the carriage when trouble flared.

A spokesman for the British Transport Police (BTP) confirmed a 46-year-old man was arrested on board the service by an off-duty officer.

The man was arrested on suspicion of causing actual bodily harm.

BTP officers met the train – which was ferrying hundreds of Suffolk commuters into the capital – as it arrived into Liverpool Street station and took him into custody.

'Paramedics from London Ambulance Service also attended and the victim, who received a cut to his right cheek, was taken to Whitechapel hospital,' the BTP spokesman added.