The Taliban's new top operations officer in southern Afghanistan had been a prisoner at the Guantanamo Bay detention center, the latest example of a freed detainee who took a militant leadership role and a potential complication for the Obama administration's efforts to close the prison.

U.S. authorities handed over the detainee to the Afghan government, which in turn released him, according to Pentagon and CIA officials.

Abdullah Ghulam Rasoul, formerly Guantanamo prisoner No. 008, was among 13 Afghan prisoners released to the Afghan government in December 2007. Rasoul is now known as Mullah Abdullah Zakir, a nom de guerre that Pentagon and intelligence officials say is used by a Taliban leader who is in charge of operations against U.S. and Afghan forces in southern Afghanistan.

The officials, who spoke anonymously because they are not authorized to release the information, said Rasoul has joined a growing faction of former Guantanamo prisoners who have rejoined militant groups and taken action against U.S. interests. Pentagon officials have said that as many as 60 former detainees have resurfaced on foreign battlefields.

Pentagon and intelligence officials said Rasoul has emerged as a key militant figure in southern Afghanistan, where violence has been spiking in the last year. Thousands of U.S. troops are preparing to deploy there to fight resurgent Taliban forces.

One intelligence official told the Associated Press that Rasoul's stated mission is to counter the U.S. troop surge.

Although the militant detainees who have resurfaced were released under the Bush administration, the revelation underscores the Obama administration's dilemma in moving to close the detention camp at Guantanamo and figuring out what to do with the nearly 250 prisoners who remain there.

In one of his first acts in office, President Barack Obama signed an executive order to close the jail next year. The order also convened a task force that will determine how to handle remaining detainees, who could be transferred to other U.S. detention facilities for trial, transferred to foreign nations for legal proceedings or freed.

More than 800 prisoners have been imprisoned at Guantanamo; only a handful have been charged. About 520 Guantanamo detainees have been released from custody or transferred to prisons elsewhere in the world.

A Pentagon tally of the detainees released show that 122 were transferred from Guantanamo in 2007, more than any other year.

The Pentagon's preferred option is to hand them over to their home governments for imprisonment. But the Defense Intelligence Agency's growing list of former prisoners that have rejoined the fight shows that, in some cases, that system does not work.

According to the Pentagon, at least 18 former Guantanamo detainees have "returned to the fight" and 43 others are suspected of resuming terrorist activities. The Pentagon has declined to provide a complete list of the former prisoners they suspect are now on the battlefield.

According to case documents assembled by the U.S. military for a 2005 review of Rasoul's combatant status at Guantanamo, the Afghan was captured in 2001 in Konduz.

Armed with a gun and sitting in the car of an alleged Taliban leader, Rasoul insisted to American authorities he was forced to carry the gun by the Taliban. Rasoul told the tribunal in 2005 that in fact he had surrendered with other Taliban members to the Northern Alliance in Konduz on Dec. 12, 2001.

The Northern Alliance was involved in a protracted civil war with the Taliban, and was allied with U.S. forces in the October 2001 invasion.

Rasoul told the tribunal that he and others were then handed over to the Americans for bounties.

According to the U.S. documents, Rasoul was conscripted into the Taliban in 1995, and was seriously wounded in a bombing in 1997. He returned to the Taliban in Kandahar in southern Afghanistan in 1999.

Rasoul, who hailed from Helmand province in southern Afghanistan— a Taliban stronghold— never attended a Taliban or al-Qaida training camp. A key piece of evidence against him was that he was captured with two Casio watches similar to those used in al-Qaida bombings. He said he was holding the watches for a Taliban member who lacked pockets.

He told the tribunal that he intended to return to a peaceful life in Afghanistan.

"I want to go back home and join my family and work in my land and help my family," he said, according to a U.S. military transcript of the hearing.

National Intelligence Director Dennis Blair said Tuesday that at least two Saudi detainees also turned up recently as members of al-Qaida in Yemen after they were released from Guantanamo. The Saudis had been handed over by the U.S. to Saudi Arabia, where they were supposedly rehabilitated as part of a Saudi program to reform extremists.

The Bush administration's decision to transfer militants to Saudi Arabia for rehabilitation "doesn't inspire confidence," Blair said.

But he told the House Intelligence Committee last month that the prison must be closed because of the damage it has done to America's reputation. It is too powerful a negative symbol to remain open, he said.

The jail at the U.S. base in Cuba, created by the Bush administration in 2002, has been criticized worldwide for allegations of abuse of prisoners and their legal status.