Indonesia has raised the alert level for two volcanoes in the Sunda Strait and Mollucas island chain to the second highest following increased volcanic activities.
The alert status for Anak Krakatau, a volcano formed in the Sunda Strait after the legendary explosion of Mount Krakatau in 1883, and Ibu volcano on Halmahera island in the Mollucas was raised yesterday after rumbling to life about a week ago.
Anak Krakatau is throwing out flaming rocks, the volcanology centre in Bandung city said.
People have been told to stay at least 2 kilometres from both volcanoes.
Anak Krakatau, which means "Child of Krakatau", is a magnet for tourists while many local people farm on the slopes of Ibu (Mother) volcano. People often live and farm on the slopes of volcanoes because of the rich volcanic soil.
Scientists monitoring Anak Krakatau said the volcano was not especially dangerous and was likely to continue to rumble for some time.
Anak Krakatau roared to life last November when it blasted massive clouds of smoke and flaming red rocks hundreds of metres into the sky.
The head of the country's volcanology centre said ashes from Ibu volcano had reached as high as 700 metres, but had not disturbed flights.
Indonesia has the highest number of active volcanoes of any country, sitting on a belt of intense seismic activity known as the "Pacific Ring of Fire".