A volcano in central Indonesia spit ash, rocks and smoke hundreds of meters into the air overnight, but experts say the eruption posed no threat to people living on the mountain's slopes.

The area has been on highest alert since Monday, when authorities started evacuating villages in the path of the smoke and ash. So far, around 2,500 of the 28,000 people who live on the fertile slopes have left the area.

Mount Lukon is one of the most active volcanoes in Indonesia. It erupted in 1991, killing a Swiss hiker.