On Friday a group of about 100 elderly, sick, pregnant or very young residents were transported away from the area around Mount Merapi in central Java, with officials warning that a mandatory evacuation order for thousands more could come within days.
Mount Merapi has become increasingly active in recent days, spewing clouds of hot gases and smoke and scientists say all the conditions for an eruption are present.
A "standby" alert status issued by scientists last week remained in effect. The alert is one stage below that required for the full evacuation of nearly 30,000 villagers living around the volcano.
Meanwhile the revered king of the nearby city of Yogyakarta has said he believes an eruption will happen within 10 days.
King Sri Sultan Hamengkubuwono's warning is likely to be taken seriously in Yogyakarta, just 18 kilometers from the volcano, because the city's one million residents hold him in deep, almost mystical, respect.
Merapi has been spewing clouds
of hot gas and smoke
"This is not a prediction from a mystic, but is based on scientific data and experience," he was quoted as saying by Media Indonesia daily.
Indonesia sits astride the so-called "Ring of Fire," a series of volcanoes and fault lines stretching from the Western Hemisphere through Japan and Southeast Asia to New Zealand. It has more active volcanoes than any other nation.
Merapi last erupted in 1994, sending out a searing cloud of gas that burned 60 people to death. About 1,300 people were killed when it erupted in 1930.