A senior leader of the militant Haqqani network, Haji Mali Khan, has been captured in Afghanistan, the Nato-led international force Isaf has said.
He was detained during an operation by Afghan and coalition forces in Paktia province on Tuesday, Isaf said.
He was heavily armed but did not resist, it added.
Haji Mali Khan is the senior commander in Afghanistan for the Haqqani network, blamed for some recent Afghan attacks and accused of links to Pakistan.
He is also a revered elder of the clan, the uncle of the network's leader, Siraj Haqqani, and served as an emissary between the Haqqanis and Baitullah Mehsud, the former head of the Pakistani Taliban who was killed in a suspected US missile attack in 2009.
He is accused of setting up bases in Paktia and coordinating the transfer of money for militant operations.
The BBC's Paul Wood in Kabul says Afghan officials describe him as the brain of the network.
The Haqqani are affiliated to the Taliban and have pledged allegiance to their spiritual leader, Mullah Omar. However, some in the West believe the Haqqani also have links to Pakistan's intelligence agency, an accusation Islamabad denies.
Change of focus
Isaf said the capture was a "significant milestone in the disruption of the Haqqani network", adding that the network remained a top priority for Afghan and coalition forces.
A large number of other insurgents was captured in the operation, in Jani Khel district, including Mali Khan's deputy and bodyguard.
A senior Afghan intelligence official in Paktia province told the BBC that agents had information of a major attack that was being planned on Jani Khel.
A joint Afghan-Isaf force arrested Haji Mali Khan, whose real name was said to be Ali Khan, in the village of Mana, the official said.
A senior counter-terrorism official in Kabul told the BBC: ''Haji Mali Khan was in charge of suicide attacks, other attacks, money, finance and operations. He was not as brutal as other Haqqanis when it came to dealing with locals. For that he was liked and protected from time to time."
US officials say they are close to deciding whether to label the Haqqani as a foreign terrorist organisation, and on Thursday the treasury department announced new sanctions on five individuals it said were linked to "the most dangerous terrorist organisations operating in Afghanistan and Pakistan".
Mali Khan's capture came days after the assassination of former Afghan president and negotiator Burhanuddin Rabbani, which was blamed on the network.
The killing prompted Afghan President Hamid Karzai to say on Friday that he was focusing on talks with Pakistan rather than the Taliban.
Afghan police said an attack on the Intercontinental Hotel in Kabul in June that left nine attackers, two police and 11 civilians dead, "bore the hallmarks" of the Haqqani.
The Haqqani network was also accused of carrying out a 20-hour attack last month on the Isaf headquarters and the US embassy in Kabul in which some 25 people died.
The US military accused Pakistan of helping the Haqqani in that attack.
The chairman of the Joint Chiefs of Staff, Adm Mike Mullen, said the network was a "veritable arm" of Pakistani intelligence service the ISI.
Pakistan has long denied supporting the Haqqani group, but BBC correspondents say it has a decades-old policy of pursuing foreign policy objectives through alliances with militants.
Although Islamabad denies the network has safe havens inside Pakistan, the country's former national security adviser told the BBC that it was operating in North Waziristan, in Pakistan's restive tribal belt.
"Today North Waziristan is a hot bed," said retired Maj Gen Mahmoud Durani.
The army was too overstretched to take on the Haqqanis, he added.