A small aircraft with 18 people on board is feared to have crashed on Thursday in Indonesia's Sumatra island, officials said.

The Cassa 212, carrying 15 passengers and three crew, was flying from Medan city in North Sumatra to the nearby province of Aceh when it lost contact with air traffic control, Bambang Ervan said.

"It took off at 7:18 a.m. (00:18 a.m. GMT) and was supposed to land at 8:00 a.m.," the spokesman told AFP, adding that a search and rescue team was trying to find the aircraft.

"Most probably it crashed as it sent an emergency signal," he said, adding it was not known whether there were foreigners on board.

Local search and rescue chief Suhri Sinaga said that the aircraft sent an emergency signal in the Bahorok area of North Sumatra province.

"We are trying to locate the aircraft," he told.

A helicopter chartered by U.S. giant Newmont Mining crashed on Sunday in central Indonesia, killing two people on board.

Earlier this month, an Australian and a Slovak pilot were killed when their small Cessna Grand Caravan aircraft, which was carrying fuel and food to a remote area in Papua province, went down.

Another small aircraft, which was also transporting supplies to remote villages for a Christian humanitarian association in Papua, crashed last week, killing its American pilot and two passengers.

The sprawling Indonesian archipelago relies heavily on air transport and has a poor aviation record.