Indonesian rescuers battled fog and thick jungle Saturday to recover the bodies of 18 people, including three foreigners, killed in a plane crash at the base of a mountain, officials said.

The Casa C-212 transport plane disappeared from radar screens at 3:03pm (0803 GMT) on Thursday around Mount Salak in West Java about 40 kilometres south of Jakarta near the town of Bogor, officials said earlier.

"The team is already at the location, but it's a gorge... it's quite difficult to go down and come up," air force spokesman Chaeruddin Ray said.

Low fog and slippery ground had slowed the progress of air force personnel and police at the crash site, Ray said.

"The rescue team is already trying to collect all the bodies in body bags," Ray said.

"With a plane shattering widely like that, you can imagine what condition the bodies are in."

The head of the search and rescue team, Hadi Tugiman, told AFP by telephone from the mountain that rescuers had already collected 15 of the victims and were readying a makeshift helipad to evacuate the bodies.

"They have not yet been taken down from the mountain yet, the plan is to take them out by helicopter but that depends on the weather," Tugiman said, adding that clouds still blanketed the mountainside.

Rescuers will attempt to carry out the bodies by foot along an arduous path through the forest if the weather fails to clear, he said.

The three foreigners -- from Britain, India and Singapore -- were among six civilians on board the military plane when it took off from a Jakarta air base on a short flight to test ground imaging equipment, but it never returned.

The other 12 on the plane were from the military.

The wreckage was reached for the first time early Saturday morning after two days of uncertainty over its fate.

Police have said local residents were the first to see the plane slam into the dense pocket of jungle on the mountain's slopes. Villagers also reportedly reached the wreckage before it was spotted by an air force plane Friday.

"People living around the Mount Salak area saw a plane flying on Thursday and then they heard sounds of an explosion," one police officer in the region said earlier.

The foreigners reportedly worked for Credent Technology offering services in high-resolution satellite imagery and laser scanning for mapping.

Officials plan to return all bodies from the crash to Jakarta's Halim Perdanakusuma airbase, where the plane originally departed from.

The foreign office in London and the Singaporean foreign ministry confirmed that British and Singaporean nationals were on board. An Indian diplomat in Jakarta confirmed an Indian was also on the flight.

Indonesia has one of the world's worst aviation safety records following a string of deadly disasters in recent years. The archipelago relies heavily on air as well as sea links.