The son-in-law of one of Afghanistan's best known factional leaders, Gulbuddin Hekmatyar, has been detained for questioning in Pakistan, reports say.

Ghairat Baheer was taken from his house in Islamabad early on Tuesday, an unnamed Pakistani police officer told the Reuters news agency.

It is not clear exactly why he has been detained.

However, reports say that Mr Baheer's arrest might be aimed at finding out Mr Hekmatyar's whereabouts, which have been a mystery since his expulsion from Iran in February after he condemned the US presence in Afghanistan and the country's new administration.

Opposition to US

Mr Baheer's residence in Islamabad was locked up on Wednesday.

He and all the male members of the household are believed to have been picked up in a pre- dawn raid.

A report in Pakistan's English-language newspaper, The News, said agents of the US Federal Bureau of Investigation also took part in the raid, but Pakistani police have not confirmed this.

Mr Hekmatyar's party has denied any involvement in recent attacks

In May, the US Central Intelligence Agency was reported to have fired a missile from an unmanned spy plane in what was said to be a failed attempt to kill Mr Hekmatyar.

The Karzai administration has accused Mr Hekmatyar of involvement in a chain of blasts, including a car bomb attack in Kabul last month that killed nearly 30 people.

Shortly after the attack Mr Hekmatyar expressed grief over the loss of life but reiterated a call for a war against the US forces.

Mr Hekmatyar's Hezb-e-Islami party was the main recipient of military aid from Pakistan during the war against the Soviet occupation of Afghanistan in the 1980s.

He was Afghanistan's prime minister for much of 1993, and for a brief period in 1996 before being kicked out by the Taleban later the same year.

He subsequently fled to Iran.