Sources familiar with talks between Congressional investigators and U.S. intelligence officials regarding the release of a report on the Sept. 11, 2001, terrorist attacks said there were still “serious disagreements” and predicted that the issue may have to be decided in face-to-face negotiations between Members and top Bush administration officials.

Seeking to defuse a showdown with the White House, senior members of the House and Senate intelligence committees hope to be ready by early summer to make available to the public the report addressing alleged intelligence failures prior to the attacks on the World Trade Center and the Pentagon.

The differences between Congressional investigators and officials from the CIA, FBI and National Security Agency center on releasing materials relating to a pair of specific subject areas, although the sources declined to offer any details.

The dispute raises the possibility that CIA Director George Tenet and other administration officials could still end up bargaining with lawmakers over the fate of the 800-plus-page report, which has been classified since its completion in December.

House Intelligence Chairman Porter Goss (R-Fla.), who helped oversee a joint House-Senate probe into the World Trade Center and Pentagon attacks, was more upbeat in his assessment of the discussions, however. Goss said he hopes to have an answer by the “end of this week” on how much of the document the CIA and other agencies would like to keep secret, and is aiming to publicly release the report by June 30.

Goss called the discussions between Eleanor Hill, staff director for the joint House-Senate inquiry, and intelligence officials “very positive, very forward leaning, very constructive.” Those talks, which took place on Monday and Tuesday, followed a “counteroffer” last week from the intelligence agencies’ “working group” to an earlier proposal by Hill.

Sen. Bob Graham (D-Fla.), a former chairman of the Senate Intelligence Committee and a Democratic presidential candidate, has charged that the CIA and other agencies don’t want the Sept. 11 report released because it spells out “a fuller and more complete story than they would like” of purported intelligence breakdowns. Graham was a co-chairman of the House-Senate inquiry last summer.

But other Democrats familiar with the report have declined to go as far as Graham, and Goss, a former CIA agent, rejected that allegation outright.

“There is no conspiracy, there are no sinister motives,” said Goss. He instead laid the blame for the delay on “a very bad process” covering the release of classified information by Congress.

Sen. Jay Rockefeller (D-W.Va.), current vice chairman of the Senate Intelligence Committee, agreed that the release of classified data was slowed by “a very cumbersome process.”

While the intelligence committees do have the option of declassifying the report on their own, Goss dismissed the notion as not feasible politically.

“If we declassify some things … then in two months a bomb goes off and people get hurt because of that, we would feel bad and look stupid,” said Goss.

The latest delay in releasing portions of the Sept. 11 report comes as Rockefeller threatened on Tuesday to force an investigation into the failure of U.S. forces to find any weapons of mass destruction in Iraq after the U.S.-led invasion of that country.

The threat to the United States from Iraqi nuclear, chemical or biological weapons was perhaps the main rationale offered by the United States for the effort to topple Iraqi dictator Saddam Hussein.

Senate Armed Services Chairman John Warner (R-Va.) has already suggested joint hearings with the Senate Intelligence Committee on the issue, although no such hearings had been scheduled as of Tuesday. The White House provided the Senate Intelligence panel with thousands of pages of documents on the WMD issue, according to Intelligence Chairman Pat Roberts (R-Kan.), and a top CIA official was to brief the committee on the issue during the afternoon.

Rockefeller, though, said he would seek support from other Senate Democrats for an Intelligence Committee investigation if Warner and Roberts don’t reach an agreement on how to go forward with their own probe. Under Intelligence Committee rules, any five Senators sitting on the panel can call for an investigation of a matter that falls within the committee’s jurisdiction. Rockefeller said he has already drafted a letter to that effect, although he has not begun seeking additional signatures. There are nine Republicans and eight Democrats currently on the committee.

Rockefeller and other top Democrats, including Sen. Carl Levin (Mich.), ranking member on the Armed Services Committee, now openly question whether intelligence assessments were skewed to play up the threat from alleged Iraqi chemical and biological weapons programs.

“One way or another, there will be an investigation,” said Rockefeller. “I don’t want this to be partisan or appear partisan. … But we have to really lay down a marker here.”

Warner briefly discussed the issue with Vice President Cheney on Tuesday, although the Virginian still believes that evidence of WMDs will be found in Iraq. Roberts, for his part, called for a “very thorough review of all the [intelligence] documents, of any statements made by members of the administration” on WMDs to determine what the White House was told and what officials said on the issue.