Army spokesman Brig. Gen. Sabrar Fadhilah said the Bell 412 EP helicopter lost contact with the base three minutes after taking off from Tarakan town in North Kalimantan province.

He said the aircraft was carrying four soldiers and about 400 kilograms (880 pounds) of supplies to Long Bawan, a remote town near the border with Malaysia.

Fadhilah said rescuers are searching for the helicopter in Malinau district in the same province, where it was believed to have gone down.

Indonesia, a sprawling archipelagic nation of 240 million, has been plagued by transportation accidents in recent years, including plane and train crashes and ferry sinkings. Overcrowding, aging infrastructure and poor safety standards are often to blame.