Islamabad - Pakistani security forces repelled overnight militant attacks on their positions in the troubled north-west, killing at least three insurgents, an official said Monday. The clashes occurred Sunday when rebels targeted checkpoints in Wana, the main town of South Waziristan tribal region bordering Afghanistan.

The area is the stronghold of top Pakistani Taliban commander Baitullah Mehsud, who has been blamed for dozens of deadly attacks, including the one that killed former prime minister Benazir Bhutto.

"Militants armed with rocket-propelled grenades and heavy arms attacked two posts in Wana, forcing the troops to retaliate with artillery and mortar fire," a security official said on condition of anonymity.

"At least three attackers were killed and several more were injured," he said. Suspected militant hideouts on nearby hills were also hit.

The troops did not suffer any fatalities, but one paramilitary soldier was wounded in the exchange of fire, according to the official.

Government administrators in the region confirmed the incidents, but provided no details.

Pakistan's lawless tribal region comprising seven districts is believed to be full of militant enclaves, which are used as by Taliban militants to attack US and NATO troops in Afghanistan.

Western powers say the fight against Taliban cannot be won unless these sanctuaries are tackled. The US has recently increased its drone strikes on Pakistani tribal region to eliminate the hideouts.

Separately, a bomb-disposal expert was killed Monday while defusing an explosive device near the town of Bannu in the adjoining North West Frontier Province, police said.

The bomb was planted beneath a bridge connecting the restive town with neighbouring districts. (dpa)