Qantas and Singapore Airlines flights cancelled due to Mount Anak Krakatau volcanic ash

Qantas has confirmed that a number of its services have been disrupted due to volcanic ash from the eruption of Mount Anak Krakatau in Indonesia.

Qantas told the ABC that the operational impacts include cancellations to and from Jakarta starting on Sunday.

"Our meteorologists and operations teams are closely monitoring conditions in and around Jakarta and any impact on our operations," Qantas said in the statement.

"Safety remains our highest priority. We have contacted affected customers and are providing assistance.

ABC understands that several passengers travelling from Melbourne and Sydney to Indonesia's capital were unable to fly as scheduled last night.

Singapore Airlines has also released a statement saying that 19 flights between Jakarta and Singapore have been cancelled until tonight.

At least 209 flights, including local and international flights, as well as cargo services have been cancelled on Sunday morning, according to Assistant Deputy Communication and Legal Soekarno Hatta airport, Yudistiawan, who goes with one name.

"We urge all travellers to double-check flight status and schedules through the airline's official channels before travelling," said Mr Yudistiawan.

Anak Krakatau has been erupting since late on Friday, with volcanic ash detected in the airport early on Sunday, the ministry said in a statement.

The dispersal of volcanic ash has disrupted activities in Lampung province in Indonesia's Sumatra island and Banten province on Java, said Berton Panjaitan, a spokesperson for Indonesia's disaster mitigation agency, Badan Nasional Penanggulangan Bencana (BNPB).

"BNPB urges the public to remain calm while increasing vigilance," he said.

"In the event of ashfall, people are advised to wear masks and eye protection, reduce outdoor activities, cover water sources and exercise caution when driving, as volcanic ash can reduce visibility."

Meanwhile, Muhamad Iid Mujtahiddin from the Meteorology, Climatology and Geophysics Agency (BMKG) told reporters that volcanic ash from Mount Anak Krakatau had reached a height of around 20,000 feet and was moving towards several areas, including West Java province.

The geophysics agency told people in areas potentially affected by volcanic ash to increase their vigilance and wear masks when engaging in outdoor activities.

Several schools cancelled activities on Saturday, with students and residents suffering eye irritation from the ash, while fishermen cancelled their fishing trips due to the eruption, local media outlet Kompas reported.

The disaster mitigation agency said on Saturday there was no imminent risk of a tsunami from the volcano.