Volcano on Bali erupts, flights cancelled

Four flights into Bali airport have been diverted while five out were cancelled after Mount Agung volcano erupted, spreading ash over the island's south.

An eruption of Bali's Mount Agung volcano has again disrupted flights in and out of the island. (AAP)

Bali's airport has cancelled flights following an eruption of the Mount Agung volcano that spread ash over the south of the Indonesian island.

The national disaster agency said Friday night's eruption lasted four minutes and 30 seconds and spread lava and incandescent rocks about 3 kilometres from the crater.

Ash from Mount Agung disrupted flights out of Bali's airport. Source: AAP

Nine villages experienced thick ash fall. But the agency said it wasn't raising the alert level for the volcano and its exclusion zone remains a 4km radius around the crater.

The Directorate General of Air Transportation said four flights to Bali were diverted and five flights out of the popular tourist destination were cancelled because of volcanic ash.

Agung became active again in 2017 after more than a half century of slumber following a major eruption in 1963.