The Anak Krakatau volcano in the Sunda Strait today began to spew red-hot lava flares 500 to 700 metres into the sky from its southern crater. The volcano has been showing signs of increased activity for the past 15 days.

Chief of the volcano's observation post, Anton, said the red-hot lava flares were triggered by the volcano's increased activity.

According to data recorded by the volcano's observation post, from midnight to 6am local time today, the volcano produced 74 clouds of ashes, followed by four deep volcanic quakes, 20 shallow volcanic quakes and four tremors.

Meanwhile, the Bandung-based Volcanology and Geological Disaster Mitigation Centre is still keeping the volcano's status at the third level of alert.

"Due to the emission of ashes followed by volcanic quakes lasting three to six minutes, it is dangerous for tourists to get close to the volcano's slopes. Visitors are only allowed to watch its activity from a distance of three kilometres," Anton was quoted as saying by Antara news agency.

The Mt Kelud volcano on Java island is also on the verge of eruption, with a dome of magma said to be forming under a crater lake.