Former US intelligence chief Dennis Blair says the CIA drone campaign aimed at al-Qaida is backfiring by damaging the US-Pakistan relationship. - File photo

MIRAMSHAH: A US drone strike in a Pakistani tribal area considered home to the most dangerous enemy of American troops in eastern Afghanistan killed at least four militants on Tuesday, officials said.

The unmanned aircraft fired two missiles, hitting a compound and a vehicle parked outside it in Miramshah, the main town of North Waziristan tribal district, a senior security official told AFP.

“At least four militants were killed,” the official said, adding that two others were also wounded. Another security official and an intelligence official confirmed the attack and casualties.

Washington has called Pakistan's semi-autonomous northwest tribal region the global headquarters of Al Qaeda, where Taliban and other al Qaeda-linked networks have rear bases in the 10-year war in Afghanistan.

The identity of the militants was not immediately clear, officials said.

The missiles struck in the main town close to a girls school before dawn as people were starting their Ramazan fast, an AFP reporter, close to the destroyed compound, said.

Militants immediately cordoned off the compound and were busy removing debris, he said.

Although the United States 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 militancy, but relations have soured since 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.