It is estimated that about 62,000 people living in the dangerous areas need to be evacuated.
The Center for Volcanology and Geological Hazard Mitigation (PVMBG) has raised the warning alert to level 4 (the maximum) and asked people to stay at least 9km from Mount Agung.
There has been an increase in volcanic tremors at the mount with a total of 564 recorded on September 25.
More than 1,000 people died when Mount Agung last erupted in 1963.
