ISLAMABAD - A son-in-law of Afghanistan's fundamentalist former premier, Gulbuddin Hekmatyar, has been arrested in the Pakistani capital by U.S. and Pakistani intelligence agents, a security official said Wednesday.

Doctor Ghairat Baheer was picked up in a pre-dawn raid Tuesday from his Islamabad residence by U.S. Federal Bureau of Investigation (FBI) agents and local intelligence operatives, the official told AFP on condition of anonymity.

Baheer's computers and personal files as well as his two security guards and two house maids were also arrested during the raid.

The Head of the Interior Ministry's Crises Management Cell, Brigadier Javed Cheema, refused to confirm or deny the detention.

Hekmatyar, whose whereabouts remain a mystery, has called at least twice in recent months for jihad, or holy war, against U.S.-led coalition troops in Afghanistan where they are hunting Al-Qaeda and Taleban remnants.

Baheer was taken in for questioning on Hekmatyar's whereabouts, the official said.

Hekmatyar and his followers have been named as possible perpetrators of a chain of blasts in Kabul in recent months, including the massive car bomb on September 5 in a busy marketplace which killed 30 people and injured 100.

Afghan and foreign intelligence officials believe he may have teamed up with Taleban and Al-Qaeda remnants to mount a campaign to destabilize the Afghan government.

His Hezb-e-Islami Party was the main recipient of military aid from Pakistan during the Mujahedin's war against the 1979-89 Soviet occupation of Afghanistan, during which he was based in Peshawar.

Hekmatyar's forces tried to oust the post-Soviet regime of president Burhannudin Rabbani in the early 1990s, reducing large swathes of Kabul to rubble.

He was eventually brought into the government as prime minister in 1996 but was kicked out later the same year by the Taleban.