Dozens are being treated for burns and respiratory problems after a gas cloud hit villages with even greater force than the previous eruptions.

A total of at least 69 people have now been killed.

An estimated 75,000 resident have been evacuated from the area.

Mount Merapi, one of the world's most active volcanoes, is located in a densely populated area in central Java.

The fresh eruption began late on Thursday, sending residents streaming down the mountain with ash-covered faces.

Many of the dead are believed to be children from Argomulyo village, 18km (11 miles) from the crater, the Associated Press news agency quotes emergency officials as saying.

Government volcanologist told AP: "This is the biggest eruption so far. The heat clouds went down the slopes as far as 13km (eight miles) and the explosion was heard as far as 20 kilometres away."

The authorities have decided to widen the "danger zone" around the crater from 15 km (9 miles) to 20km (12 miles).

Scientists are warning of further eruptions in the coming weeks.