Curfew is imposed in Miranshah area of NW Pakistan
A curfew is in place in and around the north-western Pakistani town of Miranshah after 10 soldiers were killed by militants on Sunday, officials say.
The heads of two other men - who the army denies were also soldiers - were discovered on Monday near the town, in the North Waziristan tribal area, according to military officials.
Sunday's violence unfolded when a military convoy was attacked.
Many al-Qaeda and Taliban militants have used North Waziristan as a base.
Reports from the area say that exchanges of fire are still being heard in the area. Local officials say people are staying indoors to escape the gunfire.
Correspondents say that while the army has fought militants across many of the tribal regions, it has so far not bowed to intense US pressure to take concerted action against the al-Qaeda-linked Haqqani network in its stronghold of North Waziristan.
Officials say that Sunday's violence began when "dozens" of militants attacked the troops.
"Militants hiding there opened fire at the soldiers with AK-47 assault rifles and RPG," a senior Pakistan army official told the Reuters news agency.
"Three gunship choppers [helicopters] were called in but the militants even fired rockets at the choppers."
The official said that troops had retaliated and killed "a number of militants."