This is the moment an excavator's brakes failed sending it rolling back down a hill before crashing in Thailand.

The heavy machinery was being taken to a construction site along an uphill forest road when the incident happened in Phuket on November 7.

Its driver was seen controlling the vehicle from the outside until he reached a spot to park the equipment.

However, the tractor rolled backward out of control when he turned off the engine as its brakes failed.

Footage shows the 10ft-tall digger sliding down the slope and falling into a ravine with the driver.

Shocked colleague Amree Phetmani said: ‘I was just taking a random video of us working and then it happened. It happened so fast I was almost hit if I had not run away from the tractor's path.'

The quick-thinking driver had climbed onto the outside of the excavator to try and escape while it was careering down the hill. He was then trapped under its tracks.

Colleague Amree immediately called for help. Rescue workers arrived and began releasing the driver from under the vehicle.

The rescuers dug the soil under the driver while he was still conscious to make space and safely pull him out.

However, due to the impact, the driver suffered from two broken legas. He was taken to the hospital and is now in stable condition and expected to be back behind the wheel of the excavator in the coming months.

Amree added: ‘It was very scary. We still don't know the reason why the brakes failed.'