JAKARTA (THE JAKARTA POST/ASIA NEWS NETWORK) - A boat carrying some 80 passengers capsized in Lake Toba, North Sumatra, yesterday (Mon) afternoon, with reports that at least one person had drowned.

Quoting local residents, medan.tribunnews.com reported that the incident occurred due to bad weather, not long after the KM Sinar Baru sailed from Simanindo at 5pm local time.

The boat capsized at 5.30pm as it was heading back to mainland Sumatra in bad weather.

The hotels on the island in Lake Toba - the world's largest volcanic lake, which is 1-1/2 times Singapore's size - were packed for the Hari Raya Puasa holidays, Indonesian media reported.

Nine of the passengers were found alive, but the rest were missing, the Detiknews website reported.

"The rescued passengers have been treated at Simanindo community health centre," Samosir Disaster Mitigation Agency head Maher Tamba said.

The boat capsized on its way to Tigaras in Simalungun, Mr Maher said. A rescue team from the National Search and Rescue Agency (Basarnas) has also been deployed, Mr Maher said.

At least 15 people died when two boats sank in rough waters in Indonesia last Wednesday.