An eruption by the Gunung Rinjani volcano on nearby Lombok Island has forced a temporary closure of Bali’s Ngurah Rai International Airport, disrupting hundreds of tourist flights from across the region and Australia.

The volcano, situated some 40 miles south of Bali, began erupting on Nov.1, sending an ash plume up to 6,500 ft. over the surrounding islands. Reports indicate the cloud had been blown as close as six nautical miles from Bali's Ngurah Rai, and completely over Bandar Udara International Airport on Lombok.

As a result, airport authorities decided to close both airports for several hours earlier this week, and have now completely stopped all operations at both airports as of Wednesday, Nov. 4, local time. Airport authorities said they will remain closed until Thursday morning, when the situation will be re-evaluated.

Ngurah Rai airport manager Trikora Harjo could not say exactly how many flights would be affected, but to date more than 690 flights have been canceled.

Low-cost carrier Jetstar posted an advisory on its website advising booked passengers not to go the airport as “conditions in the vicinity of Denpasar Airport, Bali are [currently] unsafe for flying,” and Virgin Australia also cited the Volcanic Ash Advisory Center as advising against flying and has canceled all Nov. 4 flights.

Indonesian flag carrier Garuda Indonesia issued a statement saying it has suspended flights to both Ngurah Rai Airport and Blimbingsari Airport near Banyuwangi until Thursday morning.

Singapore Airlines has postponed several flights and said it was monitoring the situation. Passengers are being advised to contact call centers regarding flights affected by the airport closure.

The closures come only months after a similar eruption of Mount Raung on the mainland island of Java and subsequent ash cloud led to hundreds of flight cancellations across Indonesia over several days in July.