Philippine archaeologists said Friday they had discovered a thousand-year old cemetery of rock coffins in a rainforest, but that tomb-raiders had found it decades earlier and stolen precious artefacts.
The coffins are rectangular holes carved into a limestone hill, a burial method documented only in two other areas of eastern Asia, the leader of the National Museum's archaeological dig, Eusebio Dizon, told AFP.
Dizon said local officials informed the museum last year about the site, in a forest about 200 kilometres (125 miles) southeast of Manila.
"(But) treasure hunters had been there before, in the 1960s and the 1970s, and a little bit in the 1980s," Dizon said.
"They would have taken metal and other implements to be sold, and thrown away the human remains since they had no use for them."
Forest rangers have since secured the site, on the top of a hill called Kamhantik, which is near a coconut plantation, according to Dizon.
He said his team had cleaned at least 10 mostly empty coffins, measuring two metres (6 feet, six inches) long, 50 centimetres (20 inches) wide and about 40 centimetres (16 inches) deep.
Fragments of human remains from one coffin were sent to a university in the United States for carbon-dating, which confirmed the site as a 10th-century settlement, he said.
More moss-covered coffins were found within the 12-hectare (30-acre) area of forest, and they will be excavated when funds become available, according to Dizon.
"There could be more items, artefacts showing how they lived," Dizon said.
Dizon could not say if the rock-coffin people were migrants or long-time residents who had learned the coffin-carving from outsiders.
Similar stone coffins had also been found in Gilimanuk in the Indonesian tourist island of Bali and some parts of Taiwan, he said.
But in both cases other types of rocks were used, with the Gilimanuk finds made of volcanic material, he added.
In the Philippine graves, Dizon said the community was believed to have used metal tools, maybe iron, to carve the holes into the limestone.
Other 10th-century residents of the islands used earthen jars and wood as coffins, he said.
The team also found evidence of houses being built atop the limestone.
Most of the known human settlements in the islands at the time were on the coasts, but the Kamhantik find was about six kilometres (three miles) inland, he said.
Explore further: New study shows South Africans using milk-based paint 49,000 years ago