Mount Anak Krakatau, a volcanic island in the Sunda Strait, has started hurling flaming rocks from its southern crater, Indonesian Antara news agency said on Thursday.

The agency quoted Anton Tripambudi, head of the monitoring post in a nearby village, as saying that the red-hot rocks shooting up from its crater have reached as high as 600 meters and are clearly visible from the nearby coast indicating that volcanic activity was set to continue.

Tripambudi said thundering sounds have been heard within a radius of three kilometers from the crater. The volcanic tremors had increased in frequency since the Bandung geological disaster center raised the alert status to level III.

There are no villages in close vicinity to the volcano, but the island is a popular tourist spot.

The Sunda Strait between Java and Sumatra became notorious for the devastating eruption of Mount Krakatau in August 1883, when the volcano exploded in one of the most violent eruptions in modern time.

The volcanic eruption was audible up to 5,000 kilometers away, and generated a tsunami which circled the globe three times. Over 36,000 people died in the disaster.

The volcano destroyed itself in the eruption, but Anak Krakatau, "the child of Krakatau," started emerging at the site in the 1930s.