MIRANSHAH – A US drone attack on a compound in North Waziristan Agency killed at least eight persons on Sunday.An unmanned aircraft fired two missiles on a compound in Shawal district, 50 kilometres southwest of Miranshah, the main town of North Waziristan tribal district, near the Afghan border, sources said.“Two missiles targeted the compound, killing eight persons,” a security official said on condition of anonymity, adding that the strike destroyed the house and triggered a fire. He said the bodies were badly mutilated and it was difficult to ascertain the identity of the dead as some of the bodies were charred. The drone attacks are a source of deep frustration and tension between the US and Pakistan. Islamabad says they violate its sovereignty and cause civilian casualties. The attacks also impede efforts to normalise the frayed relationship between Washington and Islamabad, including the reopening of Nato supply routes through Pakistani territory into Afghanistan. Islamabad blocked the routes after US airstrikes killed 24 Pakistani soldiers in November.The US has stepped up its drone campaign against militants in the tribal area but the local people are of the view that these strikes are targeting innocent people in the area. Agencies add: A drone missile struck a house in the Shawal Valley where militants were reported to be hiding.Several of the men killed were loyal to Hafiz Gul Bahadur, a top militant leader in North Waziristan, an official said on condition of anonymity.Bahadur, a commander who is believed to be allied with the Haqqani network and to support attacks against NATO forces in Afghanistan, is said to have an unofficial non-aggression pact with the Pakistani military.Last week, Bahadur’s group said it would act against anyone conducting polio vaccinations in its area, a direct threat to Pakistanis who collaborate with the United States.There has been a dramatic increase in US drone strikes in Pakistan since May when a NATO summit in Chicago could not strike a deal to end a six-month blockade on NATO supplies crossing into Afghanistan.A drone attack on June 4 killed 15 militants in North Waziristan, including senior Al-Qaeda figure Abu Yahya al-Libi.US officials consider the attacks a vital weapon in the war against extremists, despite concerns from rights activists over civilian casualties.The London-based Bureau of Investigative Journalism has said that under President Barack Obama one drone strike has hit Pakistan on average every four days.It said most of the 2,292 to 2,863 people reported to have died were low-ranking militants, but that only 126 fighters had been named. It said it had credible reports of between 385 and 775 civilians being killed, including 164 to 168 children.UN High Commissioner for Human Rights Navi Pillay last month called for a UN investigation into US drone strikes in Pakistan, questioning their legality and saying they kill innocent civilians.The UN human rights chief provided no statistics but called for an investigation into civilian casualties, which she said were difficult to track.She said UN chief Ban Ki-moon had urged states to be “more transparent” about circumstances in which drones are used and take necessary precautions to ensure that the attacks involving drones comply with applicable international law.