Islamabad, July 18: Authorities here today began debriefing 11 Pakistanis who had been held at the US detention centre at Guantanamo Bay in Cuba, a day after their return, officials said. US authorities had told their Pakistani counterparts 13 prisoners would be released but only 11 arrived overnight aboard a special plane, an interior ministry official said.

"We are not yet aware of the reasons for releasing two less than the indicated number," ministry spokesman brigadier Javed Cheema told a news agency.

He did not say how long the questioning would take or when they would be allowed to return to their homes. Fifteen Pakistanis prisoners have so far been released from the controversial camp x-ray while 43 remain under detention.

A total of 58 Pakistanis were captured in Afghanistan in November 2001 after the fall of hardline Taliban regime in a US-led campaign. They were suspected of being members of the Taliban militia its allies in Osama bin Laden's al-Qaeda network. One Pakistani prisoner was released in November last year, while three more were freed early this year.

Thousands of Pakistanis, many of them young students at religious schools in remote rural areas, went to Afghanistan to support the Taliban against the US-led coalition.

Pakistan abandoned the Taliban after the September 11, 2001 attacks in New York and Washington and became a key ally in the US-led war against terrorism.

Bureau Report