The team issued a code red Volcano Observatory Notice for Aviation, noting that a “large ash cloud” was drifting west of the volcano and that ash explosions up to 15km high could occur at any time. “Ongoing activity could affect international and low-flying aircraft,” it said.

Local authorities closed schools and ordered residents in nearby villages to stay indoors as an ash cloud spread for tens of kms around the volcano, head of the Ust-Kamchatsky municipal region Oleg Bondarenko said in a Telegram post.

One of Kamchatka’s largest and most active volcanoes, Shiveluch has had an estimated 60 substantial eruptions in the past 10,000 years, the last major one being in 2007.

It has two main parts, the smaller of which – Young Shiveluch – scientists have reported as being extremely active in recent months, with a peak of 2,800m that protrudes out of the 3,283m-high Old Shiveluch.

Bondarenko said the volcano erupted at 6.31am and that the cloud spread over Klyuchi and Kozyrevsk, villages more than 70km apart. Ash had started to fall on Klyuchi and Mayskoye, which lies about halfway between the two. “Residents are advised to stay indoors and avoid unnecessary travel,” he added.