A rescue official said four foreigners were among those confirmed dead, including a 67-year-old Singaporean, a German, an Austrian and a Swiss.

The floods, which were triggered by days of heavy rain, took place late on Sunday in Bohorok, close to the provincial capital of Medan in north Sumatra province.

A large river that flows down from nearby mountains overflowed its banks and washed away dozens of makeshift guesthouses that host tourists who come to the area to see its famous orangutan reserve.

'It was so fast. It came at about 9.30pm and washed away everything within just minutes,' said Mr Mega Sembiring, an employee at the Bukit Lawang Cottage.

'As far as I know, only Bukit Lawang Cottage and Batu Mandi hotel remain complete. We are now waiting to be evacuated,' he said.

Search and rescue officer Robert Sirait said the death toll could reach 72 people. Dozens of bodies were stacked up outside a local mosque, witnesses said.

Langkat District Chief Syamsul Arifin said the flood was caused by massive logging in the Leuser national park, a large national park nearby.

Bohorok is home to an orang utan reserve that attracts thousands of tourists every year, most of whom stay in cheap guesthouses overlooking the river.

Deforestation in Sumatra has been blamed for many landslides and floods by disrupting natural water absorption and flow. The island is home to many palm plantations that are a staple of Indonesia's economy. -- AP, AFP