At least five people were killed, up to 20 injured and several were reported missing after a volcano suddenly erupted off the coast of New Zealand's North Island on Monday, spewing a plume of ash thousands of feet into the air.

Police said more casualties were feared on White Island, where the volcano erupted at about 2:11pm.

About 50 people, New Zealanders as well as foreigners, were feared to have been nearby and several were seen near the rim of the crater minutes before the eruption.