At least 15 people are dead and 25 are missing after flash floods swept through a remote region of Indonesia's North Sumatra province before sunrise on Tuesday.

Indonesian officials said search and rescue teams have been sent to the Madina district of North Sumatra, about 780 kilometres northwest of the capital, Jakarta.

Hundreds of people fled their homes after the coastal region was inundated with floodwaters when the Sulang Aling river overflowed, said provincial spokesman Edi Syofian.

Health Ministry Crisis Centre chief Rustam Pakaya said medical supplies, food and tents were being delivered to the area, which is several hours by road from the nearest town.

Some reports say as many as 38 bodies have been recovered and as many as 2,000 people have been displaced.

Heavy seasonal rains mean flash floods and landslides are common in Indonesia, an archipelago of 17,000 islands that is home to over 200 million people.

In March an earthen dam on the southwestern edge of Jakarta burst its banks, sending two million cubic metres of water flooding into more than 400 homes, toppling telephone lines, sweeping away cars and killing at least 90 people.

With files from the Associated Press