This is the shocking moment a bullied worker killed his abusive boss with a sledgehammer.

Mok Boonmak, 54, suffered weeks of insults from his supervisor Wicha Pheunglomyen, 48, before taking revenge on the younger man at a construction camp in Chachoengsao, Thailand, on Tuesday.

CCTV footage shows a shirtless Mok holding a hammer as he walked toward his boss while he was taking a break under a canopy.

With both hands, the disgruntled worker then brought the tool down on Wicha's face, sending him falling to the floor.

Horrified workers rushed to restrain Mok, but when most of them left to call for help, he seized a sledgehammer and savagely bashed the injured Wicha again, ignoring desperate screams for him to stop.

Police and medics arrived after being notified at around 5:05 pm local time. They found a bleeding Wicha gasping for air after the blow caved in his nose bridge.

He was taken to Bang Nam Priao Hospital where he later succumbed to his injuries.

Mok was arrested and taken to the Chimplee district station for questioning. He claimed days of verbal abuse had driven him to attack his boss.

He said: 'My supervisor has been driving me to work for the past four or five days. While working, I could never satisfy him. He constantly complained and berated me even though I was older than him,

'I tried to bear with it, but that evening, he insulted me again. I couldn't take it anymore so I grabbed the hammer and attacked him while he was sitting there.'

Police Lieutenant Sitthinet Makchuay, who is leading the investigation, said: ‘We have apprehended the suspect for further interrogation at the station to proceed with legal action.

‘While he was being taken there, he was unaware that his boss had already passed away.'