A volcano in western Indonesia erupted Sunday, belching a column of ash around three kilometres into the sky, officials said.

Ash from Mount Marapi on the island of Sumatra was observed 3,000 metres (9,842 feet) above its peak, according to Hendra Gunawan, head of Indonesia's Centre of Volcanology and Geological Hazard Mitigation.

There were no immediate reports of damage or casualties after the eruption at 2:54 pm local time (0754 GMT).

"The column of ash was observed in grey colour with thick intensity leaning toward the east," Gunawan said in a statement.

"The eruption is still ongoing."

The volcano, with a peak of 2,891 metres, is on the third-highest alert level of Indonesia's four-step system and authorities imposed an exclusion zone around Marapi's crater.

"Communities around the Marapi volcano and tourists are not allowed to hike the Marapi volcano within a three kilometre radius from its crater/peak," Gunawan said.

Ahmad Rifandi, an official at the Mount Marapi monitoring station, told AFP that ash rain was observed after the eruption.

"For the ash rain, it has reached to Bukittinggi city," he said, referring to the third-largest city in West Sumatra that has a population of more than 100,000.

"It is hoped for people who have activities around Marapi mountain to wear hats, glasses and masks."

Mount Marapi, which means 'Mountain of Fire', is the most active volcano on Sumatra island.

The Indonesian archipelago sits on the Pacific Ring of Fire, where the meeting of continental plates causes high volcanic and seismic activity.

In May, its most active volcano, Mount Merapi in Java, spewed lava more than two kilometres from its crater.

The Southeast Asian country has nearly 130 active volcanoes.