In an escalation of the nation's culture war over the teaching of evolution, the National Academy of Sciences and the National Science Teachers Association announced yesterday that they will not allow Kansas to use key science education materials developed by the two organizations.

The refusal came after the groups reviewed the latest draft of the Kansas State Department of Education's new science education standards and concluded that they overemphasize uncertainties about the theory of evolution and fail to make it clear that supernatural phenomena have no place in science.

Until those issues are properly dealt with, the two groups said in a letter to state Assistant Education Commissioner Alexa Posny, the state will not be granted permission to use their science curriculum materials.

Those include the National Science Education Standards, which serve as the foundation for science curricula in virtually every state in the nation and which were written by the academy's affiliate, the National Research Council. They also include the science teachers' Pathway to the Science Standards, which help translate the NRC's guidelines for everyday use. Both are protected by copyrights.

The new draft of the Kansas education standards, written by a committee appointed by the former state education commissioner and subject to an up-or-down vote by the state education department early next month, "inappropriately singles out evolution as a controversial theory despite the strength of the scientific evidence supporting evolution as an explanation for the diversity of life on Earth and its acceptance by an overwhelming majority of scientists," the science groups said in a joint statement.

The organizations said they were also disappointed that a crucial statement present in an earlier draft had been deleted. It had defined science as "a search for natural explanations of observable phenomena." The deletion could lead students to believe that supernatural explanations also may fall within the purview of science, said Jay Labov, a senior adviser for education at the academy, which was chartered by Congress to advise it on science matters.

Kathy Toelkes, a spokeswoman for the Kansas education department, said the department was reviewing the draft standards, but not with the goal of changing the contested sections. Rather, she said, the goal is to paraphrase those parts that had been taken from the two national organizations, so that the copyright issues would become moot.

Toelkes said she anticipated that the board would approve "the substance of the standards" as written.

The standoff is a reprise of events in 1999 when the National Academy, the science teachers group, and the American Association for the Advancement of Science withheld copyright permission for materials that Kansas sought to incorporate into science education standards it developed that year. At the time the board had a majority who espoused creationism or intelligent design, beliefs that hold, respectively, that the Earth is only a few thousand years old and that complex life could not have arisen without help from a superintelligent being.

Scientific evidence indicates that the Earth is more than 4 billion years old and that evolution can explain all of life's biological complexities.

The Kansas standards were revised to accommodate scientists' complaints after anti-evolutionists lost their majority on the state board in 2000, but the balance of power recently reversed again. When a subcommittee of the board held hearings in May to debate evolution, scientific organizations boycotted the event, saying science would not get a fair hearing.

John G. West of the Seattle-based Discovery Institute, the major force behind the intelligent design movement, decried the science organizations' latest moves.

"This is clearly an effort to censor the discussion of scientific criticism of Darwinian theory by intimidation and threat," West said.

Gerald F. Wheeler, a nuclear physicist and executive director of the Arlington-based science teachers association, which represents 55,000 science teachers and others, disagreed.

"Science is not a dance card or jukebox where you can choose the songs you want," Wheeler said. "It's about what is the best explanation for the observations and the data we have. It's about the facts."