A volcanic ash cloud from Mount Sinabung hovers over Karo, North Sumatra, Indonesia June 9, 2019, in this still image taken from a social media video. Sinarisa Sitepu via REUTERS

Mount Sinabung, which has seen a spike in activity since 2010, erupted for around nine minutes on Sunday, sending clouds of volcanic ash 7km into the sky.

Although no casualties were reported, officials monitoring the volcano warned of possible fresh eruptions.

"After the eruption, from midnight until 6am, there were a few aftershocks," said Willy, a scientist at a Sinabung observatory post, who uses one name, like many Indonesians.

Authorities left unchanged the alert level for Sinabung, but urged residents to use face masks and keep indoors to guard against volcanic ashfall.

Mount Sinabung, which is 2,460m high, is among Indonesia's most active volcanoes, but had been inactive for four centuries before its 2010 eruption. Indonesia has nearly 130 active volcanoes, more than any other country./.

VNF/Reuters