Four out of 10 people in the UK think that religious alternatives to Darwin's theory of evolution should be taught as science in schools, according to a BBC poll.

The natural history broadcaster Sir David Attenborough said scientists should defend the boundary between science and religion: "Science teachers know perfectly well that science is based on evidence and that intelligent design is not based on evidence - in fact, quite the reverse."

Intelligent design (ID) is the notion that some structures within cells are too complicated to have just evolved and must have been placed there by a divine creator. "That is not a scientific statement," said Sir David. "If you inject that into science classes you are denying the very intellectual processes that you are supposed to be teaching as part of science."

When asked what should be taught in science classes, 69% said evolution, 44% said creationism and 41% said ID. When given the option of three explanations of the origin of life, 48% of the 2,112 adults polled by Ipsos Mori between January 5 and 10 opted for evolution without God, 22% chose creationism and 17% chose ID.

The Oxford University evolutionist Professor Richard Dawkins dismissed the results as "of very little interest".

"If somebody professes disbelief in evolution, it is highly probable that they know nothing about it," he added. "These ignorant people would probably welcome enlightenment. It is up to scientists to get out of their labs, from time to time, and enlighten."

The poll coincides with Horizon: A War on Science, which airs tonight on BBC2.