At least four Pakistani soldiers and nine militants have been killed during a shoot-out with "terrorists" in the restive northwestern tribal belt close to the border with Afghanistan.

According to a Saturday statement released by the Pakistani army, the clashes took place in the Pre Ghar mountainous area in the tribal regions on the border between North and South Waziristan.

"At least nine terrorists were killed in a cordon and search operation. Four soldiers also embraced martyrdom," the statement read.

Pakistani armed forces launched a massive operation against Taliban terrorists in North Waziristan in June 2014, after a deadly raid on the Karachi International Airport ended Islamabad's faltering peace talks with the pro-Taliban militants.

The army also started an offensive in Khyber in October 2014, carrying out air raids and using ground troops, artillery, and mortars.

Pakistan stepped up its anti-terror campaign following a late 2014 attack on an military-run school in the northwestern city of Peshawar, which claimed the lives of about 150 people, mostly children.

The army says it has managed to kill more than 2,700 militants over the past months.

The semi-autonomous tribal regions on Pakistan’s border with Afghanistan have been a hideout for Takfiri militant groups during the past years. The al-Qaeda and Taliban militants use the mountainous border area to launch attacks in both countries.

Insecurity and violence have been increasing across the region following the US-led 2001 invasion of neighboring Afghanistan.

Thousands of Pakistanis have lost their lives by the wave of violence and militancy sweeping across the country.