The FBI has been accused of covering up a key case file detailing evidence against corrupt government officials and their dealings with a network stealing nuclear secrets. The assertion follows allegations made in The Sunday Times two weeks ago by Sibel Edmonds, an FBI whistleblower, who worked on the agency's investigation of the network. She says the FBI was investigating a Turkish- and Israeli-run network that paid high-ranking American officials to steal nuclear weapons secrets. These were then sold on the international black market to countries such as Pakistan and Saudi Arabia. One of the documents relating to the case was marked 203A-WF-210023. Last week, however, the FBI responded to a freedom of information request for a file of exactly the same number by claiming that it did not exist. But The Sunday Times has obtained a document signed by an FBI official showing the existence of the file. The freedom of information request ... was made ... by an American human rights group called the Liberty Coalition, acting on a tip-off it received from an anonymous correspondent. Edmonds [said] that members of the Turkish political and diplomatic community in the US had been actively acquiring nuclear secrets. They often acted as a conduit, she said, for Inter-Services Intelligence (ISI), Pakistan's spy agency, because they attracted less suspicion. She claimed corrupt government officials helped the network, and venues such as the American-Turkish Council in Washington were used as drop-off points. Edmonds is the subject of a number of state-secret gags preventing her from talking further about the investigation she witnessed. "[These gags were] invoked not to protect sensitive diplomatic relations but criminal activities involving US officials who were endangering US national security," she said.