Scores of flights between Australia and Bali have been delayed, cancelled or turned back because of ash from the eruption of the island's Mount Agung.

Multiple Jetstar, Qantas, Virgin and Air Asia flights have been affected between Thursday night and Friday morning.

A view of the Mount Agung volcano erupting in November last year. Credit:AP

Twelve Jetstar flights, including routes between Denpasar and Sydney, Perth, Melbourne, Adelaide and Cairns, were cancelled.

"Due to volcanic ash cloud caused by Mount Agung in Bali, it is currently not safe to operate flights to or from Denpasar Airport," a statement published on Jetstar's website said.