The decision was a blow to Christian conservatives who have pressed for the teaching of creationism in schools but opponents and supporters of the concept said it could also energize and spread the campaign to put it on the curriculum.

"They will be back," Rev. C. Welton Gaddy, president of the Interfaith Alliance, told a conference-call discussion hosted by the alliance and the American Institute of Biological Sciences,

"There are people in this nation who want to use public institutions and government resources to impose on the population their particular views of religion.

"When you are convinced that you are right and everyone else is wrong, you don't stop trying to advance your belief," he said.

Intelligent design holds that some aspects of nature are so complex that they must have been the work of an unnamed creator rather than the result of random natural selection, as argued by Charles Darwin in his 1859 theory of evolution.

Opponents argue it is a thinly disguised version of creationism - a belief that the world was created by God as described in the Book of Genesis - which the Supreme Court has ruled may not be taught in public schools.

In his ruling that the Dover Area School District in Pennsylvania acted illegally by including intelligent design in ninth-grade biology classes, the judge condemned the "breathtaking inanity" of the policy of the school board, all but one of whom have now been ousted by local voters.

"Any asserted secular purposes by the board are a sham and are merely secondary to a religious objective," he said.

John Calvert, managing director of Intelligent Design Network Inc., a research organization based in Kansas, predicted the decision would help the intelligent design movement by sparking further debate over the issue.

"This isn't going to go away," he said.

MORE TO LIFE...

Calvert accused the judge of promoting a materialist view of nature and banning any criticism of evolution.

"He is making evolution a religion by not allowing honest discussion," Calvert said. "You can't reduce life to just physics and chemistry."

In October 2004, Dover became the first US school district to include intelligent design in the science curriculum. The six-week trial was closely watched by Christian conservatives in other states who plan similar initiatives.

The debate is so much in the spotlight that President George W. Bush has said he thinks intelligent design should be taught alongside evolution.

Jonathan King, professor of molecular biology at Massachusetts Institute of Technology, said the ruling may have a wider effect on the teaching of science.

"This may not come back directly focused on biology," King said. "I think we are going to see efforts to set back teaching about global warming. We are going to see efforts to argue that the solar system did not actually materially evolve.