By Rob Taylor and Amie Ferris-Rotman
KABUL (Reuters) - A secret U.S. military report says that the Taliban, backed by Pakistan, are set to retake control over Afghanistan after NATO-led forces withdraw from the country, The Times newspaper reported on Wednesday.
Lt Col Jimmie Cummings, a spokesman for the NATO-led International Security Assistance Force (ISAF), confirmed the document's existence but said it was not a strategic assessment of operations.
"The classified document in question is a compilation of Taliban detainee opinions. It's not an analysis, nor is it meant to be considered an analysis," he said.
Nevertheless, it could be interpreted as a damning assessment of the war, now dragging into its eleventh year and aimed at blocking a Taliban return to power, or possibly an admission of defeat.
It could also reinforce the view of Taliban hardliners that the group should not negotiate peace with the United States and President Hamid Karzai's unpopular government while in a position of strength.
The document cited by Britain's The Times said that Pakistan's powerful security agency, the Inter-Services Intelligence (ISI), was assisting the Taliban in directing attacks against foreign forces, a charge often denied by Islamabad.
The allegations drew a strong response from Pakistani Foreign Ministry spokesman Abdul Basit. "This is frivolous, to put it mildly," he said. "We are committed to non-interference in Afghanistan."
The Times said the "highly classified" report was put together by the U.S. military at Bagram air base in Afghanistan for top NATO officers last month. The BBC also carried a report on the leaked document.
Large swathes of Afghanistan have already been handed back to Afghan security forces, with the last foreign combat troops due to leave by the end of 2014.
But many Afghans doubt their army, security forces or police will be able to take firm control of one of the world's most unstable countries once foreign combat troops leave.
The U.S. embassy in Kabul declined to comment on the report.
The accusations will likely further strain ties between Western powers and Islamabad, which has long denied backing militant groups seeking to topple the U.S.-backed government in Kabul.
Pakistani Foreign Minister Hina Rabbani Khar was visiting Kabul on Wednesday on a mission to repair strained diplomatic ties with Afghanistan's government and to meet Karzai to discuss possible peace talks with the Taliban.
Pakistan is currently reviewing ties with the United States which have suffered a series of setbacks since a unilateral U.S. raid that killed Osama bin Laden on Pakistani soil in May last year humiliated Pakistan's powerful generals.
A November 26 cross-border NATO air attack that killed 24 Pakistani soldiers deepened the crisis.
Pakistan is seen as critical to U.S. efforts to stabilize Afghanistan, a feat one foreign power after another has failed to accomplish over the country's turbulent history.
Islamabad has resisted U.S. pressure to go after insurgent groups like the Taliban and the Haqqani network, and argues Washington's approach overlooks complex realities on the ground.
"They (the Taliban) don't need any backing. Everybody knows that after 10 years, they (NATO) have not been able to control a single province in Afghanistan because of the wrong policies they have been following," Pakistani Senator Tariq Azim, a member of the Senate's Defence Committee, told Reuters.
Pentagon spokesman George Little said: "We have long been concerned about ties between elements of the ISI and some extremist networks."
Little said U.S. Defense Secretary Leon Panetta "has also been clear that he believes that the safe havens in Pakistan remain a serious problem and need to be addressed by Pakistani authorities".
The document's findings were based on interrogations of more than 4,000 Taliban and al Qaeda detainees, the Times said, adding that it identified only few individual insurgents.
A State Department spokesman and Britain's Foreign Office both declined comment on the report.
Despite the presence of about 100,000 foreign troops, violence in Afghanistan is at its worst since the Taliban were ousted by U.S.-backed Afghan forces in 2001, according to the United Nations.
The Taliban announced this month they would open a political office in the Qatari capital Doha to support possible peace talks with the United States.
But there has also been talk of efforts to hold separate talks in Saudi Arabia because Karzai fears his government could be sidelined by U.S. talks with the Taliban.
The report could boost the Taliban's confidence and make its leaders less willing to make concessions on key U.S. demands for a ceasefire and for the insurgency to renounce violence and break all ties to al Qaeda.
Hoping to gain credibility with a population still haunted by memories of the Taliban's harsh rule from 1996-2001, the group has tried to improve its image as its fighters battle NATO and Afghan forces.
The Times said the document suggested the Taliban were gaining in popularity partly because the austere Islamist movement was becoming more tolerant.
"It remains to be seen whether a revitalized, more progressive Taliban will endure if they continue to gain power and popularity," it quoted the report as saying.
"Regardless, at least within the Taliban, the refurbished image is already having a positive effect on morale."
(Additional reporting by Dan Magnowski in KABUL and Qasim Nauman in ISLAMABAD; Writing by Michael Georgy; Editing by Nick Macfie)