MAKASSAR: At least 15 people were killed and dozens missing after flash floods left hundreds of houses buried in mud on the Indonesian island of Sulawesi, authorities said Tuesday.

A search and rescue operation was underway to find missing people feared swept away by floods and mud after three rivers in North Luwu regency overflowed due to torrential rains, the island's disaster mitigation agency said.

"As of this afternoon, we have received reports from local residents who said their relatives have gone missing. There are dozens of them missing in total," North Luwu mitigation and rescue agency head Muslim Muchsin told AFP.

Hundreds of houses as well as government offices and public facilities were engulfed in three to five metres (10-16 feet) of mud. "We can only see the roofs of the houses from a distance," Muchsin added.

As many as 2,000 residents were taking refuge at temporary shelters in North Luwu, the agency said, but the floods and mud were hampering efforts to distribute supplies.