Indonesia on Thursday raised the danger alert level for an erupting volcano that sparked a killer tsunami at the weekend, after earlier warning that fresh activity at the crater threatened to trigger another deadly wave.

A senior official at the Krakatoa observatory said, "We've raised the status of (the volcano) since this morning because there's been a change in the eruption pattern,".

A crater collapse on the volcanic island at high tide on Saturday sent waves up to 5 metres (16 feet) high smashing into the coast on the Sunda Strait, between the islands of Java and Bali.

Authorities have warned that the crater of Anak Krakatau, or child of Krakatau, remains fragile, raising fears of another collapse and tsunami, and have urged residents to stay away from the coast.

At least 430 people were killed, with 1,495 people injured and another 159 were missing.

Nearly 22,000 people have been evacuated and are living in shelters.

Indonesia, a vast Southeast Asian archipelago, is one of the most disaster-hit nations on Earth due to its position straddling the so-called Pacific Ring of Fire, where tectonic plates collide.

(Featured image : Daily Express)