Photo illustration shows Pakistani army soldiers patrolling the mountainous area of Pash Ziarat in North Waziristan. A US drone strike on Saturday killed at least three Islamic militants in Datta Khel area of North Waziristan, near the Afghan border, security officials said

A US drone strike on Saturday killed at least three Islamic militants in Pakistan's restive tribal region near the Afghan border, security officials said.

The strike took place in the Datta Khel area of North Waziristan, known as a bastion of the Taliban and Al-Qaeda. The drone targeted a moving vehicle and fired two missiles, they said.

"The identity of the militants was immediately unclear but this area is mostly occupied by members of the militant commander Gul Bahadur's group," a security official in Peshawar told AFP.

Another official on the ground in Miranshah said that the vehicle had been driving through a village 35 kilometres (around 20 miles) west of Miranshah, the headquarters of North Waziristan tribal district, when it was hit.

"We have reports that two militants of Gul Bahadur group were also injured in the attack," he told AFP on condition of anonymity because he was not authorised to speak to the media.

The security officials said that the vehicle was engulfed in flames after the attack and militants cordoned off the area, not allowing anybody to go closer, while they removed the bodies.

The Al-Qaeda-linked Haqqani network in North Waziristan, blamed for some of the deadliest attacks in Afghanistan, is one of the thorniest issues between Islamabad and Washington.

Washington has long demanded that Pakistan take action against the Haqqanis, whom the United States accused of attacking the US embassy in Kabul last September and acting like the "veritable arm" of Pakistani intelligence.

Pakistan has in turn demanded that Afghan and US forces do more to stop Pakistani Taliban crossing the border from Afghanistan to launch attacks on its forces.

There has been a dramatic increase in US drone strikes in Pakistan since May, when a NATO summit in Chicago failed to strike a deal to end a six-month blockade on convoys transporting supplies to coalition forces in Afghanistan.

Islamabad and Washington have been seeking to patch up their fractious relationship in recent months, with the supply route reopening, after a series of crises in 2011 saw ties between the "war on terror" allies plunge.

But attacks by unmanned US aircraft remain contentious -- they are deeply unpopular in Pakistan, which says they violate its sovereignty and fan anti-US sentiment, but American officials are said to believe they are too important to halt.

Washington considers Pakistan's semi-autonomous northwestern tribal belt as the main hub of Taliban and Al-Qaeda militants plotting attacks on the West and in Afghanistan.