The unmanned aircraft fired two missiles, hitting a vehicle and a house in the Hisokhel village of lawless North Waziristan tribal district, security officials told AFP.
"A US drone fired two missiles on a vehicle in Hisokhel village and at least four militants were killed," a senior Pakistani security official said.
A nearby house was also damaged in the missile strike, he added.
The identities of the militants killed in the attack, which took place some 30 kilometers (18 miles) east of Miranshah, the main town of North Waziristan, were not immediately clear, he said.
Another security official and a local intelligence official confirmed the attack and casualties.
The attack came as the world observed the 10th anniversary of the 9/11 terrorist attacks on the United States.
Although the US does not publicly confirm drone attacks, its military and the CIA in Afghanistan are the only forces that deploy the unmanned Predator aircraft in the region.
North Waziristan is the headquarters of the Haqqani leadership and the main militant bastion in the semi-autonomous tribal belt.
The Haqqani network is considered the deadliest enemy of US troops in eastern Afghanistan. It was founded by Jalaluddin Haqqani and is run by his son, Sirajuddin, both designated "global terrorists" by Washington.
The group has been blamed for some of the worst anti-US attacks in Afghanistan, including a suicide attack at a US base in the eastern province of Khost in 2009 that killed seven CIA operatives.
Around two dozen drone strikes have been reported in Pakistan since elite US forces killed Al-Qaeda chief Osama bin Laden in a suburban home near Pakistan`s main military academy in Abbottabad, close to the capital, on May 2.
The raid humiliated Pakistan and prompted allegations of incompetence and complicity in sheltering bin Laden.
Pakistan is seen as a key ally for the United States in its fight against Islamist militancy, but relations soured after the bin Laden raid, which both countries say was carried out without Islamabad being warned.
Drone attacks are unpopular among many Pakistanis, who oppose the alliance with Washington and who are sensitive to perceived violations of sovereignty.
US officials have accused Pakistani intelligence of playing a double game with extremists, including the Afghan Taliban and the Haqqani network, in order to exert influence in Afghanistan and offset the might of arch-rival India.
Washington`s pressure on Islamabad to launch a decisive military campaign in North Waziristan, as Pakistan has conducted elsewhere in the tribal belt, has so far fallen on deaf ears.
The arrest of an important Al-Qaeda figure announced last week by Pakistani intelligence was praised by Washington and appeared to indicate a warming of ties between the two allies.
Pakistan said last Monday that its forces had arrested Younis al-Mauritani, described as a senior Al-Qaeda leader believed to have been responsible for planning attacks on the United States, Europe and Australia.
He was picked up in the suburbs of Quetta -- the main town in southwestern Baluchistan province, bordering Afghanistan and Iran -- along with two other high-ranking operatives after the US and Pakistani spy agencies joined forces. (*)
Editor: Kunto Wibisono
Copyright © ANTARA 2011
