Taliban militants in Pakistan's restive tribal area Monday killed two men they accused of spying for US forces stationed across the border in Afghanistan, officials said. The bullet-riddled bodies of an Afghan refugee and a Pakistani tribesman were found at separate places in the North Waziristan tribal district that borders Afghanistan. "Notes found with the bodies said the men were killed for spying for the US," tribal police official Wali Khan said. Islamist militants frequently kidnap and kill local tribesmen or Afghan refugees on charges of spying for the Pakistani government or US forces, who are battling a Taliban-led insurgency in war-torn Afghanistan. Pakistan's rugged tribal regions have been wracked by violence since becoming a stronghold for hundreds of Taliban and Al-Qaeda rebels who fled across the border to escape the US-led invasion of Afghanistan in late 2001.