An Indonesian passenger plane that crashed with 54 people on board in Papua province was carrying cash worth around $470,000 for remote villages, a post office spokesman said on Monday as rescue teams headed to the mountainous site where it went down.

The Trigana Air Service ATR 42-300 plane crashed on Sunday, the latest in a string of aviation disasters in the sprawling Southeast Asian archipelago.

Earlier, a search and rescue plane spotted debris believed to be from the aircraft in the heavily forested Bintang Mountains district, local police chief Yunus Wally told the Antara news agency, adding that a search team was approaching the area. (Map of Papua region: http://link.reuters.com/nak45w)

There were 44 adult passengers, five children and infants and five crew on the Trigana short-haul flight from Sentani Airport in Jayapura, capital of Papua, south to Oksibil.

All those on the plane were Indonesian nationals, a National Search and Rescue Agency (BASARNAS) official said.

Airline officials were not immediately available to respond to questions from Reuters.

There was no suggestion that the large sum of money being transported on the plane was linked to its crash.

"There were four people carrying the money, 6.5 billion rupiah ($471,500)," PT Pos spokesman Abu Sofjan said, adding that it was part of an official assistance programme for the poor and was intended to be distributed to villagers.

He said poor infrastructure in Indonesia's easternmost province meant that assistance money was often flown in by air.

A Super Puma helicopter crashed in the same area last year, said Sito, a BASARNAS communications operator in Jayapura who goes by one name. "It's the weather there, it changes all the time. In the morning it can be clear and hot and then suddenly it rains," Sito said.

The crashed ATR 42-300 made its first flight 27 years ago, according to the Aviation Safety Network. Trigana Air Service has a fleet of 14 aircraft, with an average age of 26.6 years, according to the airfleets.com database.

Trigana has been on the European Union's list of banned carriers since 2007 due to safety or regulatory concerns.

It has had 14 serious incidents since it began operations in 1991, according to the online database Aviation Safety Network.

Excluding the latest crash, it has written off 10 aircraft.

Indonesia has a patchy aviation safety record and has seen two major plane crashes in the past year, including an AirAsia flight that went down in the Java Sea, killing all 162 on board.

Indonesia's president promised a review of the ageing air force fleet in July after a military transport plane crashed, killing more than 100 people.