The body found in a shallow grave in a northern mountain town by soldiers is believed to be of a missing American Peace Corps volunteer. Philippine police launched a criminal investigation.
Maj. Gen. Rodrigo Maclang told The Associated Press there was no immediate forensic confirmation that the body belonged to Julia Campbell, 40, from Fairfax, Virginia.
The remains were found buried in a dry creek, with a foot sticking out, in the vicinity of Batad village, where she was last seen, regional police commander Chief Superintendent Raul Gonzales said.
"There is a probability that there was foul play," Gonzales told AP, adding police will now treat it as "a crime incident."
U.S. Embassy spokesman Matthew Lussenhop said American authorities could not immediately confirm it was Campbell's body, saying embassy and Peace Corps officers are helping police recover and identify the remains.
He said the Peace Corps office in Washington has been "in close touch with the family throughout this process."
Police earlier speculated that Campbell may have fallen off a cliff. She went missing April 8 in the village outside Banaue town in Ifugao province north of Manila, where she had planned to view the famed mountainside rice terraces.
Ifugao provincial police chief Senior Superintendent Pedro Ganir told AP by telephone that a stray dog had dug out one foot when soldiers discovered the body, which was placed in the creek and covered with dirt.
A pair of reading glasses was found near a trail about 50 meters (165 feet) from the body, with one of the lenses laying nearby. Police also recovered a sandal they believed belonged to the woman.
"This is no longer an accident," he said.
U.S. Peace Corps Director Ronald Tschetter flew by helicopter over Batad on Tuesday and later drove to the area, about 260 kilometers (160 miles) north of Manila, to monitor the massive search for Campbell.
"I can understand why people would want to hike in the area," he told journalists at the U.S. Embassy in Manila before hearing of the body's discovery.
"It's gorgeous ... but it's rugged, and the paths, the hiking trails in some places, are very narrow," he said, adding that the terrain was "a bit treacherous, with very steep gorges covered with heavy fauna."
After talking with Peace Corps staff and Philippine police officials, he said "there is absolutely no indication at this juncture" that Campbell may have been abducted by communist rebels or criminal elements.
He also met with President Gloria Macapagal Arroyo to thank her for the government's assistance in searching for Campbell.
On Tuesday, Philippine national police chief Oscar Calderon ruled out the involvement of communist rebels in Campbell's disappearance "because the area has been cleared of insurgents."
Tschetter said more than 80 people - including police commandos, soldiers, and volunteers - were involved in the search, backed by four helicopters and four tracking dogs.
Ganir earlier said Campbell, wearing blue denim jeans, black shirt and a shawl, was last seen buying soda from a store in Batad.
She was only wearing sandals and had bought a bus ticket to return to Manila by April 9, indicating she did not plan to extend her stay or make a long hike to a spot to look at the rice terraces, he said.
Campbell is one of 137 Peace Corps volunteers currently in the Philippines.
She had been teaching English at the Divine Word College in Albay province's Legazpi city, southeast of Manila, since October 2006. She previously taught at a public school in Donsol in nearby Sorsogon province, said Nora Gallano, assistant dean of Divine Word's College of Liberal Arts.