A US drone strike Monday killed at least four militants in Pakistan's restive tribal region near the Afghan border, officials said.

The strike took place in the Datta Khel area of North Waziristan, where the Pakistani military has since June been battling militants linked to the Taliban and Al-Qaeda.

"A US drone fired two missiles at a militant compound killing four militants," a senior security official told AFP on condition of anonymity.

The identities of those killed in the strike were not immediately known, he added.

Another security official confirmed the strike and details of the casualties.

North Waziristan is one of seven semi-autonomous tribal districts that border Afghanistan. It has been a hub for Al-Qaeda and Taliban militants since the early 2000s.

The area is generally off-limits to journalists, making it difficult to independently verify the number and identity of the dead.

Washington pressed Islamabad for years to wipe out sanctuaries in North Waziristan, which militants have used to launch attacks on NATO forces in Afghanistan.

Pakistan began a long-awaited push to clear insurgent bases from North Waziristan last June after a bloody Taliban attack on Karachi airport sank faltering peace talks.

The army has intensified its offensive since the Taliban's massacre of 153 people, 134 of them children, in a school in the northwestern city of Peshawar in December.