Two detained aides to radical cleric Sufi Mohammad have been killed during a militant ambush in Pakistan's Swat valley, the country's military says.
The pair, arrested on Friday, died when rebels attacked a convoy transporting prisoners to Peshawar, officials said.
The men - Muhammad Alam and Ameer Izzat Khan - were senior aides to Sufi Mohammed, the father-in-law of the Taliban leader in the Swat valley.
The army said one soldier was also killed in the attack.
Military officials said suspected Taliban rebels ambushed the prisoner convoy en route to Peshawar early on Saturday.
There was a gun battle between rebels and security forces, with at least one report suggesting the convoy was hit by a roadside bomb.
Muhammad Alam and Ameer Izzat Khan were among six men arrested on Friday along with another aide to Sufi Mohammad and three Afghan nationals.
They were held as the US special envoy to Afghanistan and Pakistan, Richard Holbrooke, visited Pakistan to visit people displaced by recent fighting in the Swat region between Pakistan's army and Taliban militants.
The BBC's M Ilyas Khan, in Islamabad, said they were the only significant arrests since the army launched its latest operation against militants in the Swat region one month ago.
Speaking at the end of his three-day visit on Friday, Mr Holbrooke acknowledged that the military operation in Swat appeared to be achieving its objectives.
But he said the real challenge for Pakistan would be managing the humanitarian problem caused by the fighting.
Pakistan's army has regularly publicised the numbers of suspected Taliban fighters killed in its ongoing military operation in Swat, but there has been little news of the Taliban leadership of senior clerics.
Sources close to Mohammad Sufi say that his whereabouts have been unknown for the past three or four days, with his sons also reported to be missing.
Sufi Mohammad was instrumental in brokering a peace deal earlier this year between the Taliban and the government which imposed Sharia law in the district. This later fell apart when Taliban fighters moved into neighbouring districts.
Those living in temporary shelters have no clue when they will be able to return
He is also the founder of a banned militant group, Tehrik Nizam Shariat Mohammadi (TNSM).
The TNSM has in the past distanced itself from the actions of Sufi Mohammad's son-in-law, Maulana Fazlullah, who is the Taliban leader in Swat.
But, our correspondent says, Mr Mohammad and his followers have been at the forefront of elements in Swat criticising the Pakistani government for its slowness in imposing Sharia law while the deal between the government and the Taliban was still in place.
The Swat operation has displaced some two million people in Pakistan's north-west, raising fears of a humanitarian crisis in overstretched camps for those forced to leave their homes.
Rebels have also launched attacks away from the fighting.
On Friday a bomb exploded at a mosque in Upper Dir, in north-western Pakistan, during Friday prayers, killing at least 38 people and wounding dozens more.
That came a week after a gun an bomb attack in Lahore, Pakistan's cultural capital, which the Taliban claimed was a retaliation for the Swat offensive.