MIRAMSHAH, Aug 10: At least 18 suspected militants were killed and six others injured when a US drone fired two missiles at a compound in Kharonai village near Miramshah in North Waziristan on Wednesday.

According to a foreign news agency, 21 people were killed in the pre-dawn attack.

Sources said the compound belonged to the Sirajuddin Haqqani group and those killed were Afghan nationals and local tribesmen. A car and a motorcycle parked in the courtyard were destroyed.

According to witnesses, “unknown volunteers” cordoned off the area soon after the attack and retrieved the bodies and the injured from the debris. They took the injured to an unspecified hospital.

Reuters adds: The attack came just days after Pakistan called for “clear terms of engagement” in the US-Pakistan relationship.Among those targeted were members of the Haqqani network responsible for the worsening insurgency in easternAfghanistan, and foreign militants.

“The dead included local Taliban as well as some Arabs and Uzbek nationals,” an intelligence official said.

It was the largest strike since July 12, when US drones killed 48 suspected militants in North Waziristan.

Drone strikes have been a major source of friction between the United States and Pakistan, with ties at their worst since US Special Forces killed Al Qaeda chief Osama bin Laden in a secret raid in the garrison town of Abbottabad in May.

Last week, President Asif Ali Zardari called for “clear terms of engagement” between the two countries in the fight against Al Qaeda and Taliban militants operating in the country. He did not spell out the terms of engagement, but they likely involvemore consultation on drone strikes as well as greater oversight of CIA activities in Pakistan, military experts said.

While Pakistan in the past was seen to have given tacit support to the drone campaign in its militant-infested northwest region, the red lines appeared to have been crossed with the Abbottabad raid.

Some Afghan insurgents belonging to the Haqqani network fighting US-led foreign forces in Afghanistan were among the dead in Wednesday’s strike, the intelligence official said.

It was not immediately known if any high-profile militants were among the dead. Militants often dispute official account of such strikes.

Initial reports said five militants were killed in the attack, but officials said the toll had gone up to 21 after more bodies were found from the rubble of the compound.

The latest strike took the death toll of suspected militants in such attacks since the beginning of June to more than 160.