The Pakistani military and a senior US diplomat confirmed on Wednesday that the Afghan Taliban's top military commander, Mullah Abdul Ghani Baradar, had been captured.
Baradar, the most senior Taliban commander ever arrested in Pakistan, was picked up in the southern city of Karachi this month in a raid by Pakistani and US agents.
The capture came as US forces spearheaded one of NATO's biggest offensives against the Taliban in Afghanistan in an early test of US President Barack Obama's troop surge policy.
It also comes as momentum builds for talks with the Taliban to end a war Western commanders say they can't win militarily.
Officials in Kabul and in the Maldives, the Indian Ocean state, said Taliban-allied representatives and members of Afghanistan's parliament held secret talks at a resort there in January.
They did not give details but said more meetings would be held.
Pakistan wants to play a major role in any peace talks and limit the influence in Afghanistan of its old rival, India.
Pakistan has said little about the rare arrest of a top member of a Taliban leadership council the United States says has long been based in Pakistan.
"At the conclusion of detailed identification procedure, it has been confirmed that one of the persons arrested happens to be Mullah Baradar," the military said.
It gave no details, citing security reasons.
US special envoy Richard Holbrooke also confirmed the arrest but declined to give details.
"It is a significant development," he told reporters in Kabul. "We commend the Pakistanis for their role in this and it is part of a deepening cooperation between us."
US officials and analysts said it was too soon to tell whether Pakistan's cooperation against Baradar would be extended to other top militants on the US hit list.
The arrest followed months of behind-the-scenes prodding by US officials who saw inaction by Islamabad as a major threat to their Afghan war strategy.
Though nuclear-armed Pakistan is a US ally, anti-US sentiment runs high and many people have long been suspicious of the US-led campaign against militancy and oppose any US security operations in Pakistan.
"HE IS WITH US"
A Pakistani intelligence official said security agents had been searching for Baradar in the southwestern city of Quetta, where the United States says the Taliban leadership is based.
"Sensing that he might be arrested, he somehow slipped out of Quetta and into Karachi, maybe in disguise. That's where we arrested him, about four days back," said the official, who declined to be identified.
The United States was involved in Baradar's interrogation, the official said.
Asked if the Taliban commander could help with any Afghan reconciliation process, the Pakistani agent said: "It might lead to that eventually ... Anything is possible but so far we have not come to that."
Pakistan's US-backed government has vowed to eradicate Islamist militancy. The security agencies have long nurtured Muslim holy fighters, beginning with in the anti-Soviet war in Afghanistan in the 1980s, and later in Indian Kashmir.
Analysts say the security forces have for years tolerated Taliban supply and support networks, seeing the Islamists as a tool against growing Indian influence in Afghanistan.
The previous arrest of a senior Taliban leader in Pakistan, in 2007, did not lead to a crackdown on Pakisani sanctuaries.
Separately, police in Karachi arrested a suspected Pakistani Taliban commander while unknown gunmen ambushed a vehicle carrying militants in the Kurrum region on the border, killing six Taliban and wounding two, police and officials said.
Earlier on Wednesday, a US drone fired a missile into the North Waziristan region on the Afghan border, killing at least three militants, Pakistani intelligence officials said.
There was no information about the identity of those killed or of three men wounded in the strike, they said.
Pakistan objects to the drone strikes, saying they are a violation of its sovereignty and complicate its efforts against militancy.
The Pakistani army has made gains against militants battling the state over the past 10 months but it has ruled out a major offensive against Afghan Taliban factions on its soil, saying its forces are already stretched.