This is the dramatic moment a group of Indonesian climbers was caught by surprise when the volcano they were ascending erupted on Friday.

Filmer Shopan Pengestu and his team were making breakfast on the slopes of Mount Merapi in Central Java when they heard a loud rumble coming from the nearby crater.

They looked up to see a huge cloud of ash rising into the air.

The sudden eruption took hundreds of climbers by surprise and Pengetsu's group can be heard in the video calling for others further up the slope to take cover.

Fortunately, there were no serious injuries, although one person was reported to have fallen when running for cover.

A government department confirmed the eruption to media and added that it launched ash up to 5,500 metres into the air.