The chairman of the House Science Committee sharply criticized NASA yesterday after the agency's top climate scientist and several public affairs officers complained of political pressure intended to prevent public discussions of global warming.

"Good science cannot long persist in an atmosphere of intimidation," the chairman, Representative Sherwood Boehlert, Republican of New York, said in a letter to NASA's administrator, Michael D. Griffin.

"Political figures ought to be reviewing their public statements to make sure they are consistent with the best available science," Mr. Boehlert said. "Scientists should not be reviewing their statements to make sure they are consistent with the current political orthodoxy."

The New York Times first reported the complaints on Saturday.

The climate scientist, James E. Hansen, director of NASA's Goddard Institute for Space Studies in Manhattan, and several other National Aeronautics and Space Administration employees said Bush administration appointees at headquarters had demanded to review his lectures and publications in advance. Moreover, senior agency officials were to have had the right to stand in for him in interviews with reporters.

"NASA is clearly doing something wrong, given the sense of intimidation felt by Dr. Hansen and others who work with him," Mr. Boehlert said in his letter. "Even if this sense is a result of a misinterpretation of NASA policies — and more seems to be at play here — the problem still must be corrected."

Dean Acosta, Dr. Griffin's press secretary, said in the article Saturday and repeated yesterday that officials were not trying to censor Dr. Hansen or anyone else but were simply reinforcing rules that applied to everyone at the agency.

"NASA is committed to open and full communications," Mr. Acosta said. "Our policy, which is similar to that of any other federal agency, corporation or news organization, is that any NASA employee speaking on the record, issuing a press release, or posting information on our Web site, must coordinate such activities with the Office of Public Affairs. No exceptions."

Some Republican lawmakers defended the agency and criticized Dr. Hansen.

"It seems that Dr. Hansen, once again, is using his government position to promote his own views and political agenda, which is a clear violation of governmental procedure in any administration," said Bill Holbrook, a spokesman for Senator James M. Inhofe of Oklahoma, the chairman of the Senate Committee on the Environment and Public Works. "Public affairs offices exist to coordinate communications with the press, and it appears that NASA communicators are simply fulfilling their professional obligations."

For nearly 20 years, Dr. Hansen has called for action to limit heat-trapping smokestack and tailpipe emissions linked to global warming.

But during the last two years, citing growing evidence of dangerous climate shifts ahead, he occasionally criticized the administration's approach to the climate problem, and in October 2004 he said in a lecture that he planned to vote for Senator John Kerry, the Democratic presidential nominee.

Web logs and e-mail exchanges on climate science and science policy buzzed yesterday with various opinions on the imbroglio over Dr. Hansen, from those asserting that Dr. Hansen had simply succeeded in drawing attention to his views to those saying the whole matter was a side show compared with the more important quandary of how to act to avoid dangerous climate change.

"Now the debate is all about whether Hansen should be able to speak or not," said Roger A. Pielke Jr., the director of the Center for Science and Technology Policy Research at the University of Colorado. "And what we're not talking about is what we can actually do about climate change."

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