All 18 people on board a small plane that crashed in Indonesia's mountainous northern Sumatra region were killed, a rescue agency official said on Saturday.

Search and rescue teams have found all of the bodies at the site of Thursday's crash in the Bahorok area. The search had to be called off on Friday because of bad weather.

Sumarbono, of the National Search and Rescue Agency, said the bodies would be taken out by helicopter.

Chief of National Transportation Safety Committee Tatang Kurniadi declined to comment on the reason for the crash of the Casa 212 aircraft, operated by Nusantara Buana Airlines, which was on a flight from Medan city to Kutacane town.

But Kurniadi said pilots had to be careful about bad weather at this time of year.

The sprawling Indonesian archipelago relies heavily on air and sea transport, but poor infrastructure has led to frequent accidents. It was Indonesia's fourth air crash in a month.