20 hikers missing after volcano erupts in east Indonesia: rescue official

Twenty hikers, nine of them from Singapore, were reported missing Friday after Mount Dukono on Indonesia's eastern Halmahera island erupted, spewing a smoke cloud some 10 kilometres (6.2 miles) into the air, a rescue official told.

"Our team is on its way. It is not yet confirmed if there are injured people. Based on reports, there are about 20 people being searched for," local rescue official Iwan Ramdani said by telephone.

He confirmed the 20 were all hikers, even though the area had been closed to visitors since April 17 after scientists observed an increase in volcanic activity.

Lana Saria, head of the government Geology Agency, said the early-morning eruption was accompanied by a "booming sound" and a thick smoke column rising some 10 km from the summit of Mount Dukono in the North Maluku province.

"The direction of the ash distribution leans northward, so residential areas and Tobelo City need to be vigilant for... volcanic ash rain," she said in a statement.

The smoke could be dangerous for public health, Lana added, and risked disrupting transportation services.

Indonesia, a vast archipelago nation, experiences frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire" where tectonic plates collide.

Mount Dukono is currently on the third-highest alert level of Indonesia's four-tiered alert system.

Since December, the Center for Volcanology and Geological Hazard Mitigation (PVMBG) has recommended that tourists and climbers do not come within four kilometres of the volcano's Malupang Warirang Crater.