A Tory MP has said that the Government’s 2020 relationships and sex education guidance has “opened the floodgates” to extreme content on sex in schools.

Miriam Cates, Conservative MP for Penistone and Stocksbridge – and a member of the Commons’ education committee, told a Westminster Hall debate that “extreme and inappropriate” sex education material was being shared with children in schools in England.

She said that “despite its intentions”, the new RSE framework had “opened the floodgates to a whole host of external providers who offer sex education materials to schools, and now children are being exposed across the country to a plethora of deeply inappropriate, wildly inaccurate, sexually explicit and damaging materials in the name of sex education”.

She cited materials from the Sex Education Forum that divided children into two groups of “menstruators and non-menstruators” and said this would lead to confusion for a teenage girl whose periods did not start.

“How does she know she’s not pregnant? Will she just assume she’s one of the non-menstruators?” she said.

She also quoted sex education provider BISH’s materials, which says that “many people” are in the middle of the spectrum in terms of whether they had a penis and testicles, or clitoris and vagina.

Ms Cates said that some RSE lessons were “actively contributing to the sexualisation and adultification of children”.

“The introduction of graphic or extreme sexual material in sex education lessons also reinforces the porn culture that is damaging our children in such a devastating way,” she said.

She added that some sex education materials included details of a wide range of sexual positions, some of which were violent, including “rough sex”, spanking and choking, aimed at pupils of 14 years old and above.

Ms Cates said one parent in her constituency was “distraught” that her six-year-old had been taught about masturbation in school, adding that encouraging pupils to talk about intimate details with adults made them more “available” and “susceptible” to sexual predators.

“Another significant concern is the use of RSE to push extreme gender ideology. Gender ideology is a belief system that claims that we all have an innate gender that may or may not align with our biological sex,” she added.

“Gender ideology claims that rather than sex being determined at conception and observed at birth, it is assigned at birth and that doctors sometimes get it wrong,” she said.

She added that this was being “pushed on children” in some schools under the guise of RSE, “with what can only be described as a religious fervour”.

She said a video produced by the Amaze group for use in schools suggested that boys who wore nail varnish or girls who liked weight-lifting could be trans.

Ms Cates said numerous resources presented “gender theory as fact”, as did visitors from external agencies, and that this had “concerning consequences”.

“There’s been a more than 4,000% rise in the referrals of girls to gender services over the last decade, and a recent poll of teachers suggests that at least 79% of schools now have trans-identifying children,” she said.