Fifteen Islamist militants have been killed and seven of their hideouts destroyed in fresh air attacks in Pakistan's lawless tribal region bordering Afghanistan, the military said.

The air strikes were carried out Sunday in the Shawal district of North Waziristan tribal district, where the army began a major offensive in June last year against Taliban and Al-Qaeda bases.

"15 terrorists were killed and 7 of their hideouts destroyed in Shawal today (Sunday) through aerial strikes," said a brief statement issued Sunday night.

The death toll could not be independently verified as the area is remote and off-limits to journalists.

In a second incident in North Waziristan, an army officer was killed when a checkpost came under militant attack on late Sunday, security officials said.

Five militants were also killed during the exchange of fire, which took place in the Dandy Kach village in North Waziristan.

"One major embraced martyrdom during the clash. At least five militants were also killed and the attack was repulsed successfully," a security official in Peshawar told AFP.

Militants also fired rockets on the checkpost, the official said and added that militants came from across the border in Afghanistan.

A second security official in Peshawar, confirmed the attack and casualties.

Pakistan has been battling a homegrown Islamist insurgency since 2004, following the US-led invasion of neighbouring Afghanistan in 2001 and the subsequent spillover of militants across the border.

Officials say more than 3,500 militants have been killed since the launch of the latest offensive last year.

Pakistan has intensified air strikes and ground attacks, as well as raids on militant hideouts, since December 2014, when a Taliban attack on a school killed more than 150 people -- mostly schoolchildren.

Scattered attacks still take place in the country, though they are fewer and of a lesser intensity than in previous years.

According to data collected by the widely-cited South Asia Terrorism Portal, Pakistan is this year on track for the fewest casualties among civilians and security forces due to militancy since 2007, the year the Tehreek-e-Taliban Pakistan (Pakistani Taliban) was formed.

US, Indian and Afghan officials have all complained that while Pakistan has shown greater willingness to tackle its internal militant threat, it has failed to take similar action against Islamist groups with outward goals such as the Afghan Taliban, the Haqqani network and Lashkar-e-Taiba.

In addition to US-built F-16s and locally made JF-17 fighter jets, Pakistan deployed a homemade drone last week that killed three militants in the same conflict zone, joining a handful of other countries with the technology.