North Waziristan is a stronghold of the Haqqani network
A US drone attack has killed at least four militants in a northwestern Pakistani tribal district bordering Afghanistan, according to security officials.
The attack took place early Saturday, at a house near Miranshah, the main town of North Waziristan tribal district, a known hide-out of Taliban and Al-Qaeda linked militants, the Pakistani officials said.
"A US drone fired two missiles at a house and at least four militants were killed," a senior security official told AFP.
"The identities of the militants killed in the drone strike were not immediately known," he said.
Two other officials confirmed the attack.
Residents said they were woken up by the sound of low flying aircraft and the noise of the missile strike.
"The house caught fire after missiles hit it and militants immediately cordoned off the area and were searching in the rubble," a local tribesman told AFP, asking not to be named.
Washington considers Pakistan's semi-autonomous northwestern tribal belt the main hub of Taliban and Al-Qaeda militants plotting attacks on the West and in Afghanistan.
North Waziristan is a stronghold of the Haqqani network -- Afghan insurgents blamed for a series of spectacular attacks on Western targets in Kabul -- and Pakistani Taliban chief Hakimullah Mehsud.
Islamabad has been resisting US pressure to launch a sweeping offensive against militants in the area.
Pakistan says the missile attacks are counter-productive, violate its sovereignty, kill civilians and fuel anti-US sentiment.
It was the fifth US drone strike reported in Pakistan since parliament in March demanded an end to such attacks.
Relations between the uneasy allies plunged into crisis after US air strikes killed 24 Pakistani soldiers on November 26.
The incident prompted Islamabad to shut its Afghan border to NATO supplies and evict US personnel from an airbase reportedly used as a hub for drones.
Despite Pakistani criticism US officials are believed to consider the drone attacks too useful to stop them altogether. They have argued that drone strikes are a valuable weapon in the war against Al-Qaeda and other Islamist militants.
Pakistan signalled last week that it was prepared to end the NATO blockade, but hopes of clinching a deal appeared to break down over the cost of transit rights.
US President Barack Obama snubbed Pakistan at a NATO summit this week, only seeing President Asif Ali Zardari in passing and voicing frustration with Islamabad.
Pakistan has been incensed by Washington's refusal to apologise for the November air strikes and US officials have so far rejected Pakistani proposals to charge several thousand dollars for each alliance truck crossing the border.
The blockade has forced NATO to rely on longer, more expensive routes through Russia and Central Asia, even as it plans a large-scale withdrawal of combat troops and hardware from Afghanistan by the end of 2014.
According to an AFP tally, 45 US missile strikes were reported in Pakistan's tribal belt in 2009, the year Obama took office, 101 in 2010 and 64 in 2011.
The New America Foundation think-tank in Washington says drone strikes have killed between 1,715 and 2,680 people in Pakistan in the past eight years.