Mount Lewotobi Laki-Laki, a 1,584-metre-high volcano on the tourist island of Flores, erupted at 11:05 am local time (0305 GMT), the volcanology agency said in a statement.
"An eruption of Lewotobi Laki-Laki Volcano occurred... with the observed ash column height reaching approximately 18,000 m above the summit," the agency said.
It warned of the possibility of hazardous lahar floods -- a type of mud or debris flow of volcanic materials -- if heavy rain occurs, particularly for communities near rivers.
There were no immediate reports of damages or casualties.
Geology agency head Muhammad Wafid said in a statement the activity level at the volcano was "very high, marked by explosive eruptions and continuous tremors".
He also urged residents to stay at least six kilometres (3.7 miles) away from the volcano and to wear face masks to protect themselves from volcanic ash.
Last month dozens of flights to and from Bali were cancelled after the volcano erupted. Volcanic ash rained down on several communities around the volcano and forced the evacuation of at least one village.
Mount Lewotobi Laki-Laki erupted multiple times in November, killing nine people and forcing thousands to evacuate, as well as the cancellation of scores of international flights to Bali.
There were no immediate reports of cancelled flights after Monday's eruption.
A customer service agent of airport operator InJourney Airports told AFP that Bali's Ngurah Rai international airport was still operating normally despite the eruption.
Indonesia's transport ministry and airport operator did not immediately respond to an AFP comment request.
Laki-Laki, which means man in Indonesian, is twinned with the calmer but taller 1,703-metre (5,587-foot) volcano named Perempuan, after the Indonesian word for woman.
Indonesia, a vast archipelago nation, experiences frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire".
Related Links
Bringing Order To A World Of Disasters
When the Earth Quakes
A world of storm and tempest
| Subscribe Free To Our Daily Newsletters |
| Subscribe Free To Our Daily Newsletters |
