Relations between NASA Administrator Sean O'Keefe and the chairman of the board investigating the space shuttle Columbia disaster have grown testy in the wake of a dispute late last week over a request to separate several senior shuttle managers from the probe.

The transfer of the officials was requested by retired Adm. Harold W. Gehman Jr., chairman of the investigative board. Gehman has moved swiftly in recent weeks to distance himself from NASA, which formally activated the panel the day of the fatal accident and has since provided support personnel and data analysis.

Although bowing to Gehman's request, O'Keefe responded in a letter on Friday that he is "convinced this course of action will be viewed as prejudging the facts before the investigation is complete."

Yesterday, some NASA officials complained privately that the senior shuttle managers were effectively being singled out for blame or a "witch hunt" before the investigation establishes the cause of the Feb. 1 accident. Some said that by reassigning NASA managers who took part in the preparation and operation of the Columbia mission, Gehman was giving credence to a popular theory of what went wrong -- that superheated gases burned through a damaged left wing upon reentry to Earth's atmosphere and that shuttle managers failed to heed, or never heard, warnings of imminent disaster being voiced by mid-level engineers.

Glenn Mahone, a spokesman for O'Keefe, said NASA had complied with Gehman's request, but said, "We don't want to prejudge the outcome of the investigation by relieving people based on public theories of what happened in the accident."

Laura Brown, a spokeswoman for the Gehman board, said, "The admiral is not questioning the personal integrity or professionalism of the people involved here.

"As he said to members of Congress, you don't want to put people in the position of investigating themselves," she said.

According to space agency and investigative board sources, those who have been reassigned include Linda Ham and Ralph R. Roe Jr., leading members of the Columbia mission management team. They were working directly with the mission review team NASA set up after the accident and briefed board members several times on evidence turned up in the investigation. Ham also responded to specific requests for information from members.

Under the terms of the agreement worked out by O'Keefe and Gehman, space agency officials who were not part of the shuttle program at the time of the accident will be assigned to replace Ham, Roe and others in assisting the probe.

Ronald D. Dittemore, the shuttle program manager, was not a concern of Gehman's. Dittemore was NASA's chief spokesman in the days after the disaster but previously removed himself from the day-to-day investigation.

Some lawmakers and congressional aides voiced dismay at O'Keefe's letter, describing it as employing "circle the wagon" tactics at a time when Congress and the public are demanding an independent and thorough investigation of the accident, which killed the seven-member crew only minutes before they were due to land.

"I'm not sure that O'Keefe fully grasps how important it is that any perception of stonewalling be addressed and any perception of conflicted interests on the part of NASA in this investigation be addressed," said Rep. Anthony D. Weiner (D-N.Y.), a member of the House Science Committee.

Rep. Bart Gordon (Tenn.), the ranking Democrat on the space and aeronautics subcommittee, said, "I'm just astonished that Mr. O'Keefe doesn't understand the fundamental concept that you can't investigate yourself."

In response to complaints from Congress that the investigative board was not fully independent, O'Keefe rewrote the board's charter three times to insulate it from any perceived or real NASA influence. The original eight-member board, made up largely of government and military officials, has also been expanded by one outside member, and Gehman plans to announce the appointment of three other new members this week, Brown said.

O'Keefe defended NASA's handling of the Columbia mission and sought to play down differences with Gehman during appearances on morning TV news programs yesterday.

"We're going to restructure our efforts [to assist the board] with non-shuttle program management personnel, folks that have not had anything at all to do with the orbit activity during that operation," he said in an interview with CNN. "And [Gehman] has viewed that as a positive development."

Meanwhile, a former document manager at the plant that manufactured Columbia's fuel tank said yesterday that the epoxy used to attach foam insulation to the tank may have been applied improperly in the area where foam snapped off and struck the left wing just after liftoff, according to the Associated Press.

John Ehlers, who oversaw the documentation of work on Columbia's tank at Lockheed Martin Corp.'s Michoud Assembly Facility near New Orleans, wrote a letter about his concerns to the plant's ethics officer on Feb. 4, three days after the shuttle disintegrated over Texas. Ehlers said in the letter that he was told workers did not allow the epoxy to dry properly in the area where the tank attaches to the shuttle.

Gehman and other board members are scheduled to brief reporters in Houston today on progress in the investigation, which has entered its fifth week. The Federal Emergency Management Agency, which has taken the lead in the search for shuttle wreckage, said over the weekend that about 14 percent (by weight) of Columbia has been recovered and delivered to Kennedy Space Center in Florida.

NASA Administrator Sean O'Keefe expressed doubts about transfers. Adm. Harold W. Gehman Jr. wanted shuttle managers transferred.