This is the shocking moment an aggressive chained monkey attacked a motorcyclist in southern Thailand on June 8.

This is the shocking moment an aggressive chained monkey attacked motorcycle rider in a motorway in southern Thailand.

Footage shows the primate chained at the back of a pickup truck trying to scratch a man’s arm who rode near the vehicle in Surat Thani province,

Onlooker Jirachaya Witthayasirimathee said the monkey jumped on every rider that came near the truck.

She said: ‘The monkey jumped every bike that came near it. I don’t understand why it does that or if it was trained to do that.’

Thailand controversially uses trained monkeys to harvest coconuts from the top of palm tree. The coconuts are then used for producing coconut milk.