Indonesian volcano spews ash

About 600 people have been evacuated in eastern Indonesia after a volcano began spewing ash, a vulcanologist said on Wednesday.

Mount Egon on Flores island started to erupt late on Tuesday, emitting grey ash up to 4,000 metres (13,000 feet) above the crater, said Muhammad Hendrasto, head of monitoring at the volcanology office in Bandung on Java island.

Authorities immediately raised the alert to orange, one notch below the highest level, and evacuated people living about 1.8 km (1 mile) from the peak of the volcano, he said.

"It is not particularly dangerous but residents nearby need to wear a mask," Hendrasto told Reuters.

Egon has shown increased activity since early this month, he said.

A 2004 eruption forced the closure of a small airport nearby after it was covered by ash.

Indonesia has the highest number of active volcanoes of any country, sitting on a belt of intense seismic activity known as the "Pacific Ring of Fire".

People often live and farm on the slopes of volcanoes because of the rich volcanic soil.

In the past two years, at least three volcanoes in Indonesia - Mount Merapi, Kelud and Anak Krakatau - have shown signs of activity, but all are relatively quiet now.