Abu Sayyaf Islamic militants have decapitated seven Christian hostages and sent their heads to troops on the southern Philippine island of Jolo
The men - six construction workers and a factory worker, all of whom were Christian - were seized on Monday near the town of Parang in Jolo.
The military has vowed to intensify its efforts to track down the group.
Philippine troops have been fighting Islamic militants holed up in Jolo's mountainous terrain for several months.
Abu Sayyaf is the smallest of four Muslim rebel groups in the Philippines, with about 400 members.
The group is thought to have links with both al-Qaeda and the regional militant group Jemaah Islamiah, and has been blamed for a number of kidnappings and bombings in the region.
Militants ordered civilians to deliver two of the heads to a military camp and the other five heads were left at a second camp later on Thursday, officials said.
The men's remains were recovered from a village on Friday.
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