In a new report, ‘Too Much, Too Young’, the organisation says sex education should not be made mandatory for all primary schools, contrary to the wishes of some lobby groups.

It expresses alarm over some of the resources that are already recommended for primary-aged children by local councils and concludes that control of sex education should remain firmly in the hands of school governors and parents.

The report details sex education resources recommended for primary school children that show images of full frontal nudity, including erect penises, and illustrations of couples having sex, alongside detailed explanations. Other resources for children as young as five describe masturbation and oral sex.

Local councils endorsing some of the materials include Brighton and Hove, Derby City, Gloucestershire and Birmingham City.

“Any reasonable parent reading this publication will see that these resources are simply not suitable for primary-aged children and that today’s sex education is quite unlike anything they had at school,” the report reads.

“Although the right of parents to withdraw their children from sex education is very likely to remain in place, no child should be exposed to materials of this nature.”

Mike Judge, of the Christian Institute, said there was “clearly a problem” with the judgement of local councils that believe such resources to be suitable for primary school children.

He said parents must be fully consulted about materials used in sex education classes and have the opportunity to veto any they find unsuitable.

The report recommends that parents contact their children’s schools to find out which materials they are using in sex education lessons and approach the head teacher if they have concerns about the content.

If the school fails to address the concerns of parents, then the report recommends that parents withdraw their child from sex education lessons.

“This is, of course, a last resort but it may well be the only one you feel is available to you,” the report says.

Earlier in the week, Christian Institute director Colin Hart welcomed as “good news” the expressed intentions of Education Secretary Michael Gove to resist attempts to make sex education mandatory for primary schools in England.

Mr Hart expressed concerns, however, over the announcement from Public Health Minister Anne Milton last week of plans for a new Sexual Health Strategy that will go further than the previous government’s work on sexual health.

“We shall strenuously oppose any attempt to sideline parents, or push agendas that undermine Christian beliefs about marriage and family life,” he said.