A suspected U.S. drone aircraft fired two missiles at a house in Pakistan's North Waziristan region on the Afghan border on Thursday, killing four militants, Reuters qouted Pakistani intelligence officials as saying. The strike came as the Pakistani army is preparing an offensive against Pakistani Taliban militants in neighbouring South Waziristan. The drone fired at a house 3 km (2 miles) north of Miranshah, the main town in North Waziristan, and at least three Afghan Taliban members were among the four dead, the officials said. "The owner of the house is a member of the Haqqani network," said one of the intelligence officials, referring to veteran Afghan militant commander Jalaluddin Haqqani, whose men attack foreign forces in much of eastern Afghanistan. The United States, struggling with an intensifying insurgency in Afghanistan, stepped up attacks by its drones in September last year. It has launced 42 drone strikes this year compared with 32 last year, according to a Reuters tally of reports from Pakistani security and district government officials and residents. -- SPA