Suspected Islamic militants decapitated a taxi driver in northwestern Pakistan over suspicions he was a U.S. spy and a frequent visitor to an American military base in Afghanistan, an intelligence official said Wednesday.

The man's body was found Tuesday near the town of Angoor Ada in South Waziristan, a tribal region close to the Afghan border, the official said on condition of anonymity because he was not authorized to speak to the media.

The man, identified as Khan Mati, had been missing since April 17. He frequently traveled to Afghanistan and was suspected of visiting a U.S. military base in Birmal, a town in the eastern part of the country, the official said.

Mati was the second taxi driver to be abducted and killed in Angoor Ada over such suspicions in little more than a week.

Pro-Taliban militants have been blamed for killing scores of local tribesmen accused of working with Pakistani authorities or spying for the U.S. military in Afghanistan.

Pakistani military officials say Arab, Central Asian and Afghan militants suspected of links with Al Qaeda and the Taliban operate in South Waziristan and neighboring North Waziristan, where violence has escalated this year.

Pakistan is a key ally of the United States in its war against terrorism and it has deployed about 80,000 troops to border regions to track down terror suspects.

In southwestern Pakistan, meanwhile, a bomb ripped through the home of an Afghan refugee, killing him, his mother, wife and two sons, ages 10 and 14, senior police officer Qazi Abdul Wahid said Wednesday.

The refugee had his hands blown off in the explosion Monday, suggesting "he was handling the bomb," Wahid said. Parts for assembling a homemade bomb and a timer were found in the rubble of the home, he said.

Wahid said police were investigating whether the Afghan had links to attacks targeting railroads, security forces, gas fields and pipelines in Baluchistan. The violence is blamed on renegade tribesmen demanding an increase in royalties for resources extracted from their territories, but authorities have said unnamed "foreign elements" are involved.