Three or four officers, including a lieutenant colonel, are being investigated by military officials for violation of discipline, military spokesman Major General Shaukat Sultan told reporters, without naming the suspects.

Aljazeera learned that the US Federal Bureau of Investigation (FBI) arrested the officers in Afghanistan’s southeastern Zabul province, and later handed them over to the Pakistani army.

They were transferred for interrogation to the Shahbaz airbase in Pakistan’s Baluchistan province.

Switched sides

Pakistan was a lonely supporter of the Taliban militia in neighbouring Afghanistan, before switching sides in the wake of the 11 September 2001 attacks against the United States.

A US-led coalition ousted the Taliban in late 2001 for harbouring what the US claimed were "terrorists".

President Pervez Musharraf, a staunch ally of the US-led war against "terrorism", has banned several Islamist groups including Kashmiri separatist organisations.

Pakistan's Islamic parties oppose Musharraf's pro-US stance

Among the groups were Jaish Muhammad, or Army of Muhammad, and Harakat-al-Mujahidin al-Almi, or International Movement of Holy Warriors. The groups have been accused of attacking Westerners in Pakistan in recent months, apparently in retaliation for Musharraf's move to back the US-led “war on terror”.

Other groups are suspected of involvement in sectarian violence in Pakistan that has claimed hundreds of lives, mainly of minority Shias.

Many of the attacks are blamed on Sunni Muslim organisations the Pakistani government labels "terrorist".

It was not clear if the detained officers were believed to be linked to any of those groups.