By Thomas Ferraro

WASHINGTON, June 5 (Reuters) - Congressional staffers questioned FBI whistle-blower Coleen Rowley on Wednesday as a former head of the counterterrorism center at the CIA prepared to testify as the first witness in a joint probe of the failure of U.S. intelligence to stop the Sept. 11 attacks.

Cofer Black, a 27-year veteran of the CIA, had been expected to appear as early as on Thursday before a closed-door meeting of the intelligence committees of the U.S. Senate and House of Representatives. But late on Wednesday, his testimony was pushed back until at least next week, aides said.

They said the panels decided they needed more time to be briefed by staff as they begin to examine the performance of U.S. intelligence leading up to the Sept. 11 attacks that killed about 3,000 people in New York, Pennsylvania and outside Washington.

No date has been set for an appearance by Rowley, an FBI agent in Minneapolis critical of the agency's brass.

The FBI and CIA are a chief subject of a probe by the two congressional intelligence committees after a string of disclosures that the agencies failed to share information that could have warned of the attacks, and the Bush administration has been criticized for not being open enough about what it knew.

The intelligence panels announced after their first meeting on Tuesday they would investigate the government's overall response to international terrorism since 1986. On Wednesday, staff members began presenting a chronology of terrorism dating back to then, much of it dealing with Saudi-born Osama bin Laden, blamed by the United States for the Sept. 11 attacks.

'NOT A DAY FOR SURPRISES'

"Today was not a day for surprises. Almost everything that was presented had been known. But it was helpful to get it in an organized chronology," Senate Intelligence Committee Chairman Bob Graham, a Florida Democrat, told reporters after the two panels met for about two hours.

Graham said the committees had been receiving potentially relevant information from "a variety of sources," but declined to identify them.

Some committee staffers went to the FBI's headquarters in Washington on Wednesday to interview Rowley, while others briefed the two panels on the information they collected since beginning to prepare for the joint probe in February.

Staffers have interviewed hundreds of personnel from the CIA, FBI and other federal agencies, and also have reviewed hundreds of thousands of pages of documents.

Rowley said in a May 21 letter to FBI Director Robert Mueller that FBI headquarters should have approved a request from its Minneapolis office for a search warrant involving Zacarias Moussaoui, who was being held in August after arousing suspicions at a Minnesota flight school.

Moussaoui was in custody in Minnesota when the September attacks occurred, but was charged in December with conspiring to carry out the attacks. Authorities suspect he intended to join the 19 men who hijacked four passenger planes that day.

In the 13-page letter, Rowley said FBI officials in Washington "continued to, almost inexplicably, throw up roadblocks and undermine" efforts to obtain a warrant.

Black, 52, who a decade ago helped capture guerrilla leader "Carlos the Jackal," was head of the Counterterrorist Center at the CIA on Sept. 11. As part of a normal rotation, he recently finished a three-year stint in the post and now awaits another senior assignment.

The Counterterrorist Center includes members of the CIA as well as the FBI, National Security Agency, Customs Service, State Department and Immigration and Naturalization Service.

Both Rowley and Mueller are to make separate appearances on Thursday before the Senate Judiciary Committee.

Mueller is expected to testify before the intelligence committees the week of June 24 when the hearings are tentatively scheduled to be opened to the public. Nampa-Reuters