Indonesia's Mount Egon volcano erupts forcing 1,200 people to flee homes

More than 1,200 people have been evacuated from their homes as a volcano in eastern Indonesia spews clouds of ash and toxic gas into the air.

Officials said they had distributed thousands of gas masks to villagers around Mount Egon in eastern Flores island as the choking fumes from the volcano intensified.

All residents within three kilometres of the volcano were ordered to evacuate and roads were also closed.

Authorities said they were prepared to issue a wide-scale evacuation order if the situation deteriorated further.

"We are on a high alert and ready to evacuate any time," disaster mitigation official Silvanus Tobi said.

The volcano began rumbling last month but has become more active in recent days.

During its last serious eruption in 2008, Mount Egon blasted smoke and volcanic material nearly six kilometres into the atmosphere.

In January 2004, the volcano erupted, forcing 6,000 people to evacuate the area.

Mount Egon is one of 129 active volcanoes in Indonesia, which sits on the Ring of Fire, a belt of seismic activity running around the basin of the Pacific Ocean.