( CNN ) -- The FBI has begun a preliminary inquiry into allegations by the CIA that Senate staffers obtained unauthorized access to classified documents related to the agency 's now-defunct post-9/11 interrogation program , according to people familiar with the matter . The CIA 's charges , made in criminal referrals to the Justice Department , are in contrast to Senate Intelligence Committee Chairman Dianne Feinstein 's accusations last week that the agency spied on computers used by committee staffers at a CIA facility to investigate the Bush-era interrogation program . The committee staff has produced a 6,300-page report on the program , which critics say violated prohibitions on torture and exceeded legal guidance from the Justice Department . But the report remains in limbo , awaiting a declassification review by the CIA , which has disputed some of Senate findings . The unusual dispute has raised tensions between the agency and lawmakers charged with overseeing the agency 's activities . Feinstein is usually one of the intelligence community 's staunchest allies in Congress . Justice Department officials have tried to avoid getting drawn into the fight , and some lawmakers have questioned whether it is appropriate for Justice , as an agency in the executive branch , to probe a dispute between legislators and another agency . The FBI 's preliminary inquiry is intended to determine whether a full-fledged investigation is warranted , people familiar with the matter said . McClatchy Newspapers first reported the FBI inquiry . CIA Director John Brennan has disputed Feinstein 's accusations . Speaking at the Council on Foreign Relations last week , he said `` when the facts come out on this , I think a lot of people who are claiming that there has been this tremendous sort of spying and monitoring and hacking will be proved wrong . '' Documents that prompted the dispute relate to an internal review by former CIA Director Leon Panetta and , according to the agency , were intended to help summarize material it was providing to the committee . The documents were plainly labeled as for internal use and were not supposed to be reviewed by the committee . Feinstein said Senate staffers found the documents in the course of their work that were put in the computer system either on purpose by a whistleblower or perhaps in error , and that they corroborated some of the committee 's findings that the agency now says it disagrees with . She said committee staff routinely sees such documents and did n't violate any classified restrictions . Dean Boyd , a CIA spokesman , said in an op-ed published in USA Today that the agency acted properly after it discovered Senate staffers may have accessed and retained sensitive documents stored in a CIA computer network . `` These documents were privileged , deliberative , pre-decisional executive branch material that implicated separation of powers concerns , '' Boyd wrote . `` Because we were concerned that there may have been a breach or vulnerability in the CIA local area network on which CIA stored these documents , CIA information technology specialists were asked to conduct a limited review to determine whether these files were located on the side of the CIA network the committee was authorized to use . That review appeared to confirm the committee 's unauthorized access to the documents . ''
Preliminary inquiry over CIA allegations Senate staffers obtained unauthorized access to documents . Senate committee chair , in turn , accused CIA of spying on panel 's computers . Comment: