Hundreds of Indonesians have fled their homes after a volcano erupted spewing ash and smoke thousands of metres into the air, authorities said Wednesday.

Breathing masks and clean water have been rushed to the eastern island of Flores where the 1,703-metre (5,587-foot) high Mount Egon erupted late Tuesday, they said.

Indonesia's vulcanology office said 600 people from a village near the crater had been evacuated, but a local official said 23,000 were living in the danger zone.

"There are more than 23,000 people in three subdistricts within the danger zone," Robert Rai told AFP.

"Initial contacts with the heads of the subdistricts said that many people panicked yesterday evening because the eruption was preceded by earthquakes. But there are no figures available yet (on numbers of evacuated).

"For the time being, we have sent masks and clean water."

Authorities were thrown into confusion by the eruption, which came at around 10:15 pm (1315 GMT) as they prepared for district elections Wednesday.

Indonesia's vulcanology office said a team was already on site to monitor the volcano's activity, and that no deaths had been reported.

The Indonesian archipelago sits on the the Pacific "Ring of Fire," where continental plates collide, and is home to about 130 active volcanoes.