The headless body of one of 16 kidnapped Pakistani soldiers was found Tuesday in a tribal area near the country's border with Afghanistan.
Pakistani officials say pro-Taleban militants beheaded the soldier and threatened to kill more unless authorities release 10 of their men.
Gunmen abducted the soldiers on August 9in South Waziristan, a frontier tribal region and stronghold of Taleban and al-Qaida sympathizers.
Residents found the body in the town of Jandola. A note found nearby warned that other soldiers would be killed if the demands are not met.
Violence has escalated since pro-Taleban militants abandoned a 10-month peace deal with Pakistani authorities in neighboring North Waziristan in July.
Militants also vowed stepped up attacks following a government raid on the radical Red Mosque in Islamabad last month during which some 70 extremists were killed, including a top cleric.
Some information for this report was provided by AFP and Reuters.