The US drone program in Pakistan has probably reached the "outer limits of its utility" and robs intelligence forces of valuable information while angering Pakistanis, says a report issued by a Washington based Think Tank. The United States has ramped up its use of the unmanned weapons, with President Barack Obama ordering more strikes in 2009 than were authorised in the eight years prior. But the report by Peter Bergen and Katherine Tiedemann at the New America Foundation, a Washington think-tank, argues that the tactic is counterproductive. "The drone program has probably reached the outer limit of its utility," Bergen said in presenting the study. The weapons have reportedly killed some high-level militants in Pakistan's Federally Administered Tribal Area (FATA), including Baitullah Mehsud -- the most wanted militant in Pakistan and one-time leader of the Pakistani Taliban. But the report calculates that civilians account for 32 percent of the people killed in drone strikes from 2004 to today. The strikes also do not appear to have interrupted training programs in the tribal areas, where fighters are prepared for combat in Afghanistan or to launch attacks in the West. The report cites the example of Najibullah Zazi, a naturalised American citizen who received explosives training in Pakistan's tribal area in preparation for a planned terror attack in the United States. "He had picked up this technical knowledge in training camps in Pakistan's FATA during the fall of 2008 when the drone program was going into full swing," the report said. Meanwhile, suicide attacks in both Pakistan and Afghanistan have increased alongside the rise in drone strikes. "If the drone attacks are so successful, why is it that in 2009 you had more suicide attacks, almost all conducted by groups that are based in FATA, in Pakistan than in any year previously?" Bergen said. Assassinating militants also robs the US and Pakistani forces of potentially invaluable information that could be obtained during interrogations and evidence in the form of documents, cell phones or other materials captured along with detainees, the report said. The US military has increasingly used drone strikes as an alternative to sending troops into Pakistan or relying on Pakistani forces who have at times appeared reluctant to target militants in their territory. But Bergen said recent arrests of senior Pakistani Taliban members, including the capture of Mullah Abdul Ghani Baradar in Karachi, suggested a Pakistan change of heart. "Pakistan's a big country and FATA's a tiny part of it, so the fact that they're now picking people up in Karachi or other parts of the country is a major change," he said.