The Afghan Taliban says it has captured dozens of Pakistani soldiers following an attack on their checkpoint during a cross-border raid.
Athar Abbas, a major-general in Pakistan's army, confirmed on Wednesday that 40 Frontier Corps troops were missing after their post on the border between Pakistan's Mohmand and Bajaur districts was overrun by Afghan Taliban on Monday.
Abbas said the Taliban had handed over five of the soldiers to the Pakistani consulate in Jalalabad, in Afghanistan, but the whereabouts of the other 35 was unknown.
The Pakistani army also said it had killed 38 Afghan Taliban fighters in Bajaur on Wednesday, where commanders had previously said the Taliban were purged.
Officials said 10 soldiers were also killed in the fighting.
"At least 38 militants were killed and 10 soldiers were martyred," Zakir Hussain Afridi, the Bajaur administration chief, said as he showed 18 bodies of fighters in the presence of local forces commanders.
He said security forces destroyed two Taliban hideouts and arrested 23 fighters during the clashes.
Troops mounted another offensive in Bajaur earlier this year and declared the terrain to be free of Taliban in March.
Commanders claimed an earlier victory in February 2009, but violence returned when the military turned its attention to fighting the Taliban in South Waziristan and Swat, also in the northwest.
Pakistani troops have been fighting in Bajaur since August 2008, trying to wipe-out Taliban and al-Qaeda hideouts, but there are indications that the Taliban is trying to make another comeback.