A British man savagely punched a Thai commuter after becoming enraged when he knocked his phone to the floor and failed to apologise profusely enough.

Footage taken on a smartphone on Bangkok's Metropolitan Rapid Transit (MRT) metro line shows the Thai man bump into the tourist, causing his iPhone to fall on the ground.

Jean Yean, the woman who filmed the incident, told MailOnline: 'The Thai carelessly walked into the train at Wat Mangkorn station then hit the foreigner who's using his phone, then the foreigner got angry and the fight began.'

The British man can be seen squaring up to the frightened Thai man on the Bangkok metro on Sunday. Credit: Facebook / Jean Yean

The Thai man, wearing a striped brown shirt, tries to move away from the British man's punch on the Bangkok metro on Sunday. Credit: Facebook / Jean Yean

She noticed that it was a new iPhone 11 with 'three cameras' that fell.

The man apologised for the accident but the British man can be seen flying into a fit of rage, smashing him across the face.

The attacker, who is a head taller than the slight man, can then be seen stalking him as he moves around the train.

The yellow-shirted Thai commuter creates a distance between the attacker and his victim on Bangkok's Metropolitan Rapid Transit (MRT) on Sunday. Credit: Facebook / Jean Yean

A yellow-shirted Thai passenger and a man who appears to have been with the British traveller, try to calm the situation and stop the violence from escalating.

Both men stand in between the thug and his victim but he still manages to land a couple more blasts on the Thai man's chin.

The man got off the train at Hua Lamphong but the British tourist followed him and continued the ruck outside the train, the filmmaker said.

The man travelling with the British man, pictured second from right, hold his hand up to his companion on the Bangkok metro on Sunday. Credit: Facebook / Jean Yean

The British man can be seen stalking the slight Thai man on the Bangkok metro on Sunday. Credit: Facebook / Jean Yean

The yellow-shirted commuter gets between the attacker and the man who nudged him on the Bangkok underground on Sunday. Credit: Facebook / Jean Yean

The furious British tourist can be seen after the Thai man knocked his phone from his hand on Sunday in Bangkok. Credit: Facebook / Jean Yean

The clip was posted to Thai Facebook page Red Skull-addict, an indie media site, where many of those commenting called for the brute to be caged.

One Facebook user said: 'They should have taken the [beaten] person to the station staff. Then have taken the injured person to the police station. The wrongdoers must pay.'

Another asked: 'Why are foreigners so angry?'