WASHINGTON - A senior US official Friday denied a report that says covert American drone strikes in Pakistan have killed 385 civilians, nearly half of them children, asserting that the findings by the London-based Bureau for Investigative Journalism are faulty and uncorroborated. The unnamed official was reacting to the report released this week by the non-profit group that found CIA covert drone strikes since 2004 killed at least 2,292 people. Of those killed in the strikes, the group said it had credible reports of at least 385 civilians, including 160 children. The numbers cited by this organization are way off the mark, CNN quoted the official as saying. According to the senior US official, an estimated 2,000 militants and 50 civilians have been killed in strikes since 2001. Since May 2010, the strikes have killed 600 militants, the official said. In that same period of time, we cant confirm any non-combatant casualties, the official said. The Bureau of Investigative Journalism, which includes British and Pakistani journalists, defended its report in a statement Friday, calling it the most accurate public record yet of the CIAs drone strikes. All of our sources are credible and transparent, and where contradictory information exists, we make that clear, its editor, Iain Overton, said. It is unfortunate that instead of engaging with our work, the CIA sees fit to smear it. The report spurred immediate reaction from US officials, fearing the often violent reaction in the region to allegations of civilian casualties. The State Department also disputed the groups findings, saying the United States goes to enormous lengths to avoid killing or injuring innocent civilians. To that end, President (Barack) Obama has directed that we be exceptionally precise and surgical in addressing the terrorist threat, relying both on rigorous review procedures and all of the technological tools at our disposal to ensure that innocent civilians are protected, said Victoria Nuland, a State Department spokeswoman. We try to ensure that we only use force against those individuals who threaten us. The Bureau for Investigative Journalism findings are published in a 22,000-word database that lists details of each drone strike as compiled from news reports, researchers and lawyers examining drone attacks and leaked US intelligence reports and diplomatic cables. Among the groups findings: More than 1,100 people were injured in the 291 drone strikes known to have taken place since 2004. The group also reported that of the 291 drone attacks, at least 236 have been ordered since Obama was named president. Of the at least 2,292 people reported killed, at least 1,842 were killed in strikes since Obama took office. Accounts of the strike after strike from official and unofficial sources are so at odds that they often seem to describe different events, The New York Times reported. The debate has intensified since Obamas top counterterrorism adviser, John Brennan, clearly referring to the classified drone programme, said in June that for almost a year, there hasnt been a single collateral death because of the exceptional proficiency, precision of the capabilities weve been able to develop. The governments assertion of zero collateral deaths meets with deep scepticism from many independent experts, the report said, noting that a new report from the British Bureau of Investigative Journalism, which conducted interviews in Pakistans tribal area, concluded that at least 45 civilians were killed in 10 strikes during the last year. Others who question the CIA claim include strong supporters of the drone programme like Bill Roggio, editor of The Long War Journal, who closely tracks the strikes, the report said. The Taliban dont go to a military base to build bombs or do training. There are families and neighbours around. I believe the people conducting the strikes work hard to reduce civilian casualties. They could be 20 percent. They could be 5 percent. But I think the CIAs claim of zero civilian casualties in a year is absurd, Roggio said. Colonel David Sullivan, an Air Force pilot with extensive experience with both traditional and drone airstrikes from Kosovo to Afghanistan, said that while remotely piloted craft offered far greater opportunities to study a target and avoid hitting civilians, there is still a margin of error in drone strikes, even if it is far smaller than in traditional strikes. Zero innocent civilians having lost their lives does not sound to me like reality, Colonel Sullivan said. Never in the history of combat operations has every airborne strike been 100 percent successful.