This is the shocking moment a bus rolled uncontrollably backwards down a steep road before plunging off a hillside.

The vehicle carrying 49 passengers was travelling on a winding mountain road when it appeared to suffer a brake failure in Bataan, the Philippines.

Footage shows the bus sliding backwards on March 2 while motorists behind it were seen pulling to the edge of the road to avoid a collision.

The coach avoided motorcycles, a van, and cyclists before it hit a patch of trees and fell 20ft (6m) down a cliff.

Driver Karen Dela Pena, who was in the opposite lane, said: 'It was so scary. We immediately called the police for help after that.'

Four bus passengers were injured and taken to the hospital while authorities investigated the cause of the accident.

Police initial findings said there was a brake failure while the bus was driving uphill.

An officer from Morong Police Station said: 'The brake cylinder failed so the driver lost control.'

Investigations are still ongoing.