Every secondary school in the UK has been targeted in a new campaign promoting the teaching of creationism in science lessons. Heads of science at 5,000 schools have been sent teaching materials casting doubt on Darwin’s theory of evolution and encouraging children to consider alternative interpretations of life on earth. A booklet and two DVDs, created by Truth In Science, an influential group of academics and clergymen advocating more “balance” in GCSE and A-level science, were mailed to private and state schools this week.

One GCSE biology homework plan says teachers should consider that fossils have been artificially manufactured in China, asking pupils to write a 200-word article exposing “scientific fraud”.

The move has prompted criticism from the British Humanist Association and Ekklesia, the Christian think-tank. They have drafted a joint letter to Ofsted, urging it to write to schools saying creationist theories should not be employed in science lessons. It has reignited the debate over the place of intelligent design and creationism - the strict Biblical theory that God created the world in six days - in the syllabus.

The issue was brought into sharp focus earlier this year when teachers were being asked to consider “creationist interpretations” of fossils as part of a biology syllabus introduced by the OCR exam board. However, the Royal Society and Rowan Williams, the Archbishop of Canterbury, said creationism should be limited to religious education lessons. In April, Jacqui Smith, then schools minister, sought to defuse the row by saying that creationism should not “be used as an example of a scientific controversy”.

But this week, schools were contacted by Truth in Science - a limited company, which lists Andy McIntosh, a professor of thermodynamics at Leeds university, among its five-man board - again urging them to analyse Darwin’s theories critically. Professor McIntosh said the mail-shot and accompanying website had been bankrolled by “like-minded individuals”

frustrated at the lack of balance in science syllabuses.

George Curry, chairman of the Church Society, an evangelical Anglican organisation, and academics from Cardiff, Sheffield and Bristol universities are named as advisers.“We fully realise we are a minority, but we are a growing minority,” he told The TES.

Graham Wright, head of science at the private North Bridge House school, Camden, said: “I sent it straight back and asked to be taken off their mailing list. Only science should be taught in science lessons - intelligent design and creationism is not science.”

Andrew Copson, education officer for the British Humanist Association, said: “Thoughtful people of all persuasions should reject the use of religion to undermine truthfulness in education.”

Simon Barrow, Ekklesia’s co-director, said: “The government and its inspectorate should have no truck with superstition in the modern science classroom.”