Indonesia has raised the alert status of Mount Merapi in Java to its highest level and ordered the compulsory evacuation of thousands of residents living on the slopes of the volcano.
"This morning we raised the status of Merapi to the top alert which is the red code. Every resident has been ordered to evacuate," Subandrio, head of the Merapi section at the Centre for Volcanological Research and Technology Development, said.
Lava spills from Mount Merapi in Yogyakarta, central Java this morning
Lava could be seen flowing and thick smoke was rising from Merapi, one of the most dangerous volcanoes in the Pacific "Ring of Fire" that has been rumbling for weeks.
Despite the increased seismic activity and the flowing lava, vulcanologists could not say when the volcano was likely to erupt.
Merapi, which means "Mountain of Fire", lies near the ancient city of Yogyakarta at the centre of densely populated Java island. It killed 70 people in a 1994 eruption and 1,300 in 1930.
Indonesia, which has the world's highest density of volcanoes, has already moved about 5,000 people away from Merapi, but officials put the total number of residents on and near the mountain at around 14,000, which includes villages in Central Java and Yogyakarta provinces.
Most of those relocated to tents and shelters in safe areas are women, children and the elderly. Some return to their homes near the volcano during the day to feed livestock, local officials say. Some villagers living on the slopes or in the shadows of Mount Merapi say they will stay put until nature sends signals, or the government forces them to leave. Many fear losing property and livestock if they go.
Residents say signals would include lightning around the mountain's peak or animals moving down its slopes. Most Javanese villagers consider the mountain sacred. Every year a priest climbs to the top to make an offering. Many Indonesians also see activity in Mount Merapi as an omen of looming political unrest.
Merapi is also close to Borobudur, a 1,200-year-old temple complex that is one of Indonesia's most famous tourist sites.
Thousands of villagers were evacuated in January 1997 when Merapi became active, just months before the Asian financial crisis struck. Most Javanese, who make up the bulk of Indonesia's 220 million people, are Muslim, but many cling to a spiritual past and believe a supernatural kingdom exists on top of Merapi.