WASHINGTON — The White House has withheld for five years more than 9,000 top-secret documents sought by the Senate Select Committee on Intelligence for its investigation into the now-defunct CIA detention and interrogation program, even though President Barack Obama hasn’t claimed executive privilege.In contrast to public assertions that it supports the committee’s work, the White House has ignored or rejected offers in multiple meetings and in letters to find ways for the committee to review the records, a McClatchy investigation has found.The significance of the materials couldn’t be learned. But the administration’s refusal to turn them over or to agree to any compromise raises questions about what they would reveal about the CIA’s use of waterboarding and other harsh interrogation techniques on terrorism suspects in secret overseas prisons.The dispute indicates that the White House is more involved than it has acknowledged in the unprecedented power struggle between the committee and the CIA, which has triggered charges that the agency searched the panel’s computers without authorization and has led to requests to the Justice Department for criminal investigations of CIA personnel and Senate aides.“These documents certainly raise the specter that the White House has been involved in stonewalling the investigation,” said Elizabeth Goitein, co-director of the Brennan Center for Justice’s Liberty and National Security Program at the New York University Law School.The committee and the CIA declined to comment. In a statement to McClatchy, the White House confirmed that “a small percentage” of the 6.2 million pages of documents provided to the committee were “set aside because they raise executive branch confidentiality interests.”The White House also said that it has worked closely with the committee “to ensure access to the information necessary to review the CIA’s former program.”Speaking to reporters during a White House event, Obama said that the administration has worked with the committee to ensure that its study is “well-informed” and that he is committed to seeing the report declassified once a final version is ready. He said it wouldn’t be proper for him to comment directly on the battle between the CIA and the committee, except to say that CIA Director John Brennan had referred the issues to the “appropriate authorities and they are looking into it.”The Democratic-controlled committee has largely kept silent about the tussle with the White House, even as some members have decried what they say is the CIA’s refusal to surrender key materials on the agency’s use during the Bush administration of interrogation methods denounced by the panel chairwoman as “un-American” and “brutal.”The chairwoman, Sen. Dianne Feinstein of California, made no mention of the White House documents during a blistering floor speech Tuesday in which she charged that the CIA may have undermined the Constitution and violated the law by searching computers used by her staff to compile the study. Brennan has denied her allegations, and the White House has expressed confidence in his leadership.In question are some 9,400 documents that came to the committee’s attention in 2009, McClatchy has learned. It’s unclear whether the CIA gave the committee staff access to the materials before the White House withheld them.Obama still hasn’t formally decreed that the documents are protected by executive privilege, McClatchy has learned. Although the doctrine isn’t mentioned explicitly in the Constitution, the Supreme Court in 1974 recognized a limited power by the White House to withhold certain communications between high officials and close aides.The withholding of the documents “may not be a smoking gun” proving White House obstructionism, said Goitein, a former Senate Judiciary Committee legal adviser.Among the other explanations: The White House might have determined that the documents are not relevant to the inquiry or that they are indeed covered by executive privilege, she said.“The most nefarious explanation is that they are not privileged and the White House simply doesn’t want to hand them over,” Goitein said. “Executive privilege is generally asserted after negotiations and brinkmanship behind the scenes. People put on paper what they want to be formalized, and these negotiations by their very nature are very informal.”The committee, the CIA and the White House have held periodic talks on the materials since 2009. Their apparent failure to resolve the standoff led Feinstein to write several letters last year to Obama’s chief legal adviser, Kathryn Ruemmler, seeking a resolution, McClatchy has learned.Ruemmler didn’t respond to any of the letters.It was not known whether the materials came up during a visit by Ruemmler and White House chief of staff Denis McDonough to Feinstein and the committee’s vice chairman, Sen. Saxby Chambliss, R-Ga., on Tuesday after Feinstein delivered her speech.