RAWALPINDI: Since the last phase of Operation Zarb-i-Azb kicked off in February, at least 252 militants have been killed and 160 severely injured, while security forces have cleared 640 square kilometres of a so far uncontrolled area in Shawal Valley of North Waziristan Agency, the Inter-Services Public Relations said in a statement on Sunday.

"Major terrorist hubs" in Mana, Gurbaz, Lataka, Inzarkas and Magrotai areas have been cleared of militants. it added.

"The battle to clear the last pocket close to the Pak-Afghan border continues," the statement said, adding that all heights over 9,000 feet have been cleared.

"Terrorists' hideouts were destroyed, a cache of arms and ammunition recovered and there was virtually no communications infrastructure remaining in the Shawal area once the operation was launched in Feb this year," the statement said.

Since the beginning of the operation in June 2014, security forces have cleared 4,304 sq km in North Waziristan and "restored writ of the government in all areas, specially in remote pockets of the Federally Administered Tribal Areas", the ISPR said.

Since February, eight army men have been killed, while 39 have been injured.

Soldiers have made 150-kilometre-long tracks while conducting the operation, the statement said, adding that the ongoing operation is being conducted in extremely hostile terrain under harsh weather conditions.

"Operation is continuing in Shawal heights which are fully covered in snow, and visibility is very poor on and inside mountains," the statement added.

During the last phase of Zarb-i-Azb, return of Temporarily Displaced Persons (TDPs) is progressing according to plan, as 37,012 families in North Waziristan Agency ─ 36 per cent of TDPs ─ have returned to their homes, the statement said.

Around 94 development projects have been completed in the first and second phases in North Waziristan Agency, and 153 projects were kickstarted in phase three, the ISPR said, adding that progress on the projects was reviewed by Army Chief General Raheel Sharif.

Military operation Zarb-i-Azb was launched in North Waziristan nearly two years ago after a brazen militant attack on Karachi's international airport and the failure of peace talks between the government and Tehreek-i-Taliban Pakistan negotiators.

The number of attacks in Pakistan has fallen around 70 per cent, due to a combination of the military offensive against Taliban bases along the Afghan border and government initiatives to tackle militancy, recent reports have revealed.