Word of the killings came as U.S. Gen. David Petraeus, head of U.S. Central Command and commander of U.S. forces in Afghanistan and Iraq, arrived in Islamabad Tuesday for scheduled meetings with senior Pakistani officials.
No agenda for the talks in Pakistan — a key ally of the United States in its war on terror — has been announced, although U.S. missile strikes on northwest Pakistan's tribal areas have brought protests from civic groups and the government in Islamabad. Foreign Minister Shah Mahmood Qureshi on Monday told visiting British Defense Secretary John Hutton that such violations of Pakistani territory were "counterproductive."
Militants have responded to the attacks with a campaign of terror aimed at those accused of providing information on the whereabouts of Taliban and al-Qaida leaders.
A tribal police official, Sharif Ullah, said the bodies of the six accused spies were found at two militant strongholds in the North Waziristan tribal region near the Afghan border early Tuesday.
Five Pakistani men were shot to death in the town of Miran Shah, while the sixth man — an Afghan national — had been hanged from a tree in the town Mir Ali, he said.
Ullah said notes pinned to the bodies accused them of passing on information to Americans in exchange for money and threatened other informers with the same fate.
Militants in North Waziristan have killed at least 19 people they accused of spying for the U.S. since Dec. 21, including the new victims.
Ullah said killings of accused spies were growing in scope.
"Previously the Taliban used to kill one or two American spies, but now they've killed five Pakistanis and one Afghan," Ullah said.
The slayings came hours before a bomb wounded five police officers in Peshawar, the capital of North West Frontier Province bordering Afghanistan.
Police official Mohammed Ashraf said the explosion Tuesday hit a police vehicle when it stopped on a road in Peshawar.
Unidentified assailants planted the bomb in a section of gas pipeline that is under construction, he said, adding that the possibility of a gas explosion had been ruled out.
Peshawar is the main city in the Pakistani region close to the Afghan border where the Taliban and al-Qaida have established bases. The city has seen rising violence, including attacks on trucks carrying supplies to NATO and U.S. forces on the other side of the frontier.