Reuters/Islamabad

Air strikes killed 20 suspected militants in the restive northwest of Pakistan on Saturday, the military said, as it marked the one-year anniversary of an anti-Taliban offensive in the area.

The air strikes took place around Datta Khel in North Waziristan, the military said in a statement.

The mountainous region along the Afghan border used to be a key Taliban stronghold, with insurgents controlling all the major urban centres.

But one year ago, as NATO prepared for the complete withdrawal of combat troops from Afghanistan, the Pakistani military launched a long-awaited push to clear militant havens on the Pakistani side of the border, in a campaign known as 'Zarb-e-Azb'.

"So far, 2,763 terrorists killed, 837 hideouts destroyed. 253 tons (of) explosive recovered," military spokesman Major General Asim Bajwa said in a tweet. He said 347 officers and soldiers had also been killed.

It is unclear how many civilians have died or how reliable the casualty figures are. The military controls access to the area and journalists are only allowed in on tightly supervised reporting trips.

Nearly one million civilians were displaced by the offensive after the military ordered them to leave their homes ahead of the operation. They have still not been allowed back.

The Pakistani offensive, which followed a failed attempt to hold peace talks between the government and the Taliban, has not prevented militant groups from carrying out attacks.

In December, Taliban fighters attacked an army-run school in Peshawar, killing 134 children. They said it was revenge for the operation.