Evangelical Christian groups committed to converting young people are being allowed access to children in state schools because of the marginalisation of religious education, a new study warns.

The report, by the National Secular Society (NSS), calls on the Government to introduce a stricter code of conduct to prevent visiting groups “proselytising” during RE lessons.

The report claims that the squeezing of RE in the curriculum and the absence of trained RE teachers has created an “open door” for evangelical groups to push creationism and their own brand of sex education.

Head teachers’ leaders warned that “a line is crossed” when religious theories such as creationism were taught as if they were scientific theories. However, groups named in the report were quick to deny any suggestion they were “proselytising”. The report says: “The low priority given to RE and collective worship in many schools, combined with the short supply of qualified RE teachers and general pressure to provide sufficient teaching hours provides an ideal environment for evangelical groups to exploit.”