Chile's Calbuco volcano has erupted, spewing a giant funnel of ash high into the sky near the southern port city of Puerto Montt and triggering a red alert.

Authorities ordered an evacuation for a 10-kilometre radius around the volcano, which is the second in southern Chile to have a substantial eruption since March 3, when the Villarrica volcano emitted a brief but fiery burst of ash and lava.

The Calbuco volcano's last eruption was in 1972.