Under the cover of a benign government information-gathering program, a Defense Department official set up a network of private contractors in Afghanistan and Pakistan to help track and kill suspected militants. The official, Michael D. Furlong, hired contractors from private security companies that employed former C.I.A. and Special Forces operatives. The contractors, in turn, gathered intelligence on the whereabouts of suspected militants and the location of insurgent camps, and the information was then sent to military units and intelligence officials for possible lethal action in Afghanistan and Pakistan. Some American officials say they became troubled that Mr. Furlong seemed to be running an off-the-books spy operation. It is generally considered illegal for the military to hire contractors to act as covert spies. Officials said Mr. Furlong's secret network might have been improperly financed by diverting money from a program designed to merely gather information about the region. Moreover, in Pakistan, where Qaeda and Taliban leaders are believed to be hiding, the secret use of private contractors may be seen as an attempt to get around the Pakistani government's prohibition of American military personnel's operating in the country.