Fierce fighting erupted after up to 60 insurgents armed with rocket launchers and machine guns attacked the checkpost in Mattni village, on the outskirts of Peshawar, senior police official Nasirul Mulk Bangash told AFP.
"Two paramilitary soldiers and one policeman embraced martyrdom and six others were injured during the fighting," he said. One militant was also killed and several others wounded in the gunbattle which lasted for more than 90 minutes, but militants fled with their casualties towards Khyber tribal district, he said.
The site of the clash was near the lawless Darra Adam Khel district where militants occupied a Japanese-built road tunnel last month. Fifty militants and 15 soldiers were killed when troops cleared rebels from the tunnel.
In a separate incident on Sunday, an militant was killed and three paramilitary troops were wounded in a clash in the tribal zone of North Waziristan, officials said. The rebel threw a hand grenade at a checkpost in the crowded main market in Miranshah, the main town in the troubled region, and was killed when troops returned fire, a local administration official added.
Hundreds of people have died in recent months in clashes between pro-Taliban militants and security forces and in a wave of suicide attacks blamed on the rebels.