Schools in England will be banned from teaching sex education and gender identity to children below nine under new government proposals due to be published Thursday.
It follows concerns over the content of lessons for primary age school children, an education ministry statement said.
"Parents rightly trust that when they send their children to school, they are kept safe and will not be exposed to disturbing content that is inappropriate for their age," it quoted Conservative Prime Minister Rishi Sunak as saying.
"That’s why I was horrified to hear reports of this happening in our classrooms last year," he added.
In addition to a ban on sex education for under nines, the "contested theory of gender identity will not be taught", the ministry added.
The move follows a landmark review which last month urged "extreme caution" on prescribing masculinising or feminising hormone treatments for young people grappling with gender identity issues.
The new proposals will also include additional content on suicide prevention and the risks of viewing content promoting self harm online.
The proposals will be subject to a nine-week consultation and will be statutory once finalised.