A volcano in western Indonesia erupted twice Sunday, hurling red-hot ash and rocks up to seven kilometres into the air and forcing more than 1,000 people to flee their homes.

Mount Sinabung on Sumatra island erupted in September for the first time in three years, forcing thousands to flee their homes, and has been erupting intermittently ever since.

Early Sunday it hurled a column of ash seven kilometres (four miles) into the air, then erupted again in the afternoon.

Police and troops began evacuating residents from villages in a three-kilometre area around the volcano after the first eruption, said national disaster agency spokesman Sutopo Purwo Nugroho.

"1,293 residents living around Mount Sinabung were evacuated to safer areas," he said.

"The number of evacuees will rise."

More than 15,000 people were evacuated after Sinabung, in North Sumatra province, first rumbled back to life in September.

Indonesia has dozens of active volcanoes and straddles major tectonic fault lines known as the "Ring of Fire" between the Pacific and Indian oceans.

In August five people were killed and hundreds evacuated when a volcano on a tiny island in East Nusa Tenggara province erupted.

The country's most active volcano, Mount Merapi in central Java, killed more than 350 people in a series of violent eruptions in 2010.