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Indonesia's Mount Sinabug has been placed on "red-alert" after spewing thick plumes of smoke mile into the skyline in a spectacular display.
Residents took footage of the clouds of smoke rising from the volcano's crater, in its latest level of activity since the 2014 eruption.
A Volcano Observatory Notice for Aviation has now placed Mount Sinabug on red-alert - the highest threat level - which generally means an eruption could occur.
Authorities have also enforced a no-go zone 5km from the crater, the agency said.