Former surgeon general Richard H. Carmona yesterday accused the Bush administration of muzzling him on sensitive public health issues, becoming the most prominent voice among several current and former federal science officials who have complained of political interference.

Carmona, a Bush nominee who served from 2002 to 2006, told the House Committee on Oversight and Government Reform that political appointees in the administration routinely scrubbed his speeches for politically sensitive content and blocked him from speaking out on public health matters such as stem cell research, abstinence-only sex education and the emergency contraceptive Plan B.

"Anything that doesn't fit into the political appointees' ideological, theological or political agenda is often ignored, marginalized or simply buried," he said. "The problem with this approach is that in public health, as in a democracy, there is nothing worse than ignoring science or marginalizing the voice of science for reasons driven by changing political winds."

In one such case, Carmona, a former professor of surgery and public health at the University of Arizona, said he was told not to speak out during the national debate over whether the federal government should fund embryonic stem cell research, which President Bush opposes.

"Much of the discussion was being driven by theology, ideology, [and] preconceived beliefs that were scientifically incorrect," said Carmona, one of three former surgeons general who testified at yesterday's hearing. "I thought, 'This is a perfect example of the surgeon general being able to step forward, educate the American public.' . . . I was blocked at every turn. I was told the decision had already been made -- 'Stand down. Don't talk about it.' That information was removed from my speeches."

White House spokesman Tony Fratto rejected claims of political interference, saying Carmona had all the support he needed to carry out his mission. "As surgeon general, Dr. Carmona was given the authority and had the obligation to be the leading voice for the health of all Americans," Fratto said. "It's disappointing to us if he failed to use his position to the fullest extent in advocating for policies he thought were in the best interests of the nation."

Carmona said that when the administration touted funding for abstinence-only education, he was prevented from discussing research on the effectiveness of teaching about condoms as well as abstinence. "There was already a policy in place that did not want to hear the science but wanted to just preach abstinence, which I felt was scientifically incorrect," Carmona said.

Rep. Henry A. Waxman (D-Calif.), the House panel's chairman, called for Congress to take steps to insulate the office from political influence. "We shouldn't allow the surgeon general to be politicized," he said. "It is the doctor to the nation. That person needs to have credibility, independence and to speak about science."

Carmona, a former deputy sheriff in Arizona with expertise in emergency preparedness, came to the administration's attention because of his work helping local governments plan their response to terrorist attacks. A high school dropout and former Army Special Forces medic, Carmona eventually received undergraduate and medical degrees from the University of California at San Francisco.

He is the latest in a string of government employees to complain that ideology is trumping science in the Bush administration.

In January, the leader of the National Institutes of Health's task force on stem cells, Story Landis, said that because of the Bush policy -- which aims to protect three-day-old embryos -- the nation is "missing out on possible breakthroughs." And in March, NIH Director Elias A. Zerhouni called the Bush policy "shortsighted."

Last year, NASA scientist James E. Hansen and other federal climate researchers said the Bush administration had made it hard for them to speak in a forthright manner about global warming. In 2005, Susan F. Wood, an assistant FDA commissioner and director of the agency's Office of Women's Health, resigned her post, citing her frustration with political interference that was delaying approval of over-the-counter sales of Plan B.