Eight Indonesian airports, including two serving Jakarta, remained closed on Monday as volcanic ash from eruptions at Mount Anak Krakatau spread across the region.

Anak Krakatau, located around 150 km (90 miles) from Jakarta, began erupting late on Friday, producing lava fountains and sending volcanic ash towards the capital and Lampung province, severely disrupting air transport.

Amid the volcanic activity, schools in the affected region shifted to online classes, while ship movements were also disrupted.

With flight operations suspended, long queues of travellers were seen outside the departure halls at Jakarta's Soekarno-Hatta International Airport on Monday.

Passengers were seen demanding refunds and seeking updates on the status of flight operations.

Describing the situation at the airport, Finna, who was due to fly home to Jakarta from Malang in East Java, told the BBC: “It was very crowded because passengers from the morning flights had piled up, while those scheduled for later departures still didn't know what would happen.”

“Everyone seems to be racking their brains [figuring alternative transportation options],” Jo Shaw, who was visiting Indonesia with members of her conservation charity Save the Rhino International, told the BBC.

Meanwhile, Indonesia's Geological Agency under the Ministry of Energy and Mineral Resources (ESDM) said the continuous eruption episode of Mount Anak Krakatau in the Sunda Strait had ended after lasting about 25 hours, Antara news agency reported.

The continuous eruption began at 11:07 p.m. local time on Friday, September 4, and officially ended at 12:04 a.m. on Sunday, September 6, Head of the Geological Agency Lana Saria said in an evaluation report received on Monday.

“Following the end of that episode, Mount Anak Krakatau's volcanic activity transitioned back to Strombolian eruption characteristics, marked by the recording of three Strombolian eruption earthquakes,” Saria told the news agency.

Anak Krakatau sits in the Sunda Strait, roughly midway between the islands of Java and Sumatra. The volcano first emerged from the caldera created by the catastrophic 1883 eruption of Krakatoa, which destroyed much of the island of Krakatoa.

Sporadic eruptive activity has continued at the site since the late 20th century.

On December 22, 2018, a large section of the volcano collapsed, triggering a deadly tsunami that killed hundreds of people along the coasts of Java and Sumatra.