Jakarta - Residents were evacuated after Mount Karangetang volcano on an eastern Indonesian island began spewing lava and hot ash, threatening a major eruption, officials said Tuesday.

There were no reports of casualties in connection with the increased activity of Mount Karangetang, the officials said.

Volcanologists upgraded the alert status to the highest level on Sunday for the 1,784-metre volcano on the remote island of Siau, part of the Sulawesi chain, about 2,340 kilometres north-east of Jakarta.

Officials said residents were urged to stay outside a radius of 3 kilometres from the crater to avoid possible danger.

Rendy Rompas, an official at North Sulawesi's regional disasters agency, said more than 100 residents from several villages located on the danger zones area had been evacuated, but some of them were allowed to return homes during the day.

Local authorities also ordered a ban on farming and other activity on the slope areas, said Surono, a volcanologist from Indonesia's directorate general of vulcanology, who like many Indonesians goes only by one name. He added that people were also barred from climbing the volcano.

Mount Karangetang is known as the most active volcano in the island chain. Its activity has been increasing for weeks.

The last deadly eruption of Karangetang occurred in 1992, killing at least six villagers.

Indonesia, the world's largest archipelago nation, is prone to seismic upheaval due to its location on the so-called Pacific "Ring of Fire," an arc of volcanoes and fault lines encircling the Pacific Basin. The country has the world's highest density of volcanoes. Of its 500 volcanos, 128 are active and 65 are listed as dangerous. (dpa)