Nick Clegg has accused Prime Minister David Cameron of “dereliction of duty” by blocking plans to make sex education mandatory in all schools.

A recent report found that half of all UK school pupils are being put at risk due to inconsistent sex and relationships education – while campaigners have warned that issues including sexuality, gender, consent and domestic violence are often not routinely covered in the limited provisions that are available.

Parliament’s Education Select Committee last year recommended that inclusive sex and relationship education (SRE) should become a statutory requirement in all schools as part of PSHE- but the government rejected the plans this month.

Sources suggested that Education Secretary Nicky Morgan had been in favour of accepting the proposals – but was blocked by David Cameron, sparking a minor Cabinet feud.

Writing in the Standard, former Deputy Prime Minister Nick Clegg slammed Mr Cameron for his role in blocking the change.

The former Lib Dem leader wrote: “The announcement flies in the face of a weight of evidence which shows learning about sex and relationships in schools helps protect young people from sexually transmitted diseases, sexual harassment and bullying, and unwanted pregnancies.

“The reason, as every parent or teacher knows, is obvious: the more you know, the more you can protect yourself.

“Four key House of Commons committees have recommended that sex and relationship education should be made compulsory.

“It has also been backed by five teaching unions, the Children’s Commissioner, the Chief Medical Officer, the Association of Police and Crime Commissioners, two royal societies and six medical royal colleges.”

He added: “The fact is that by not talking to children about sex and relationships we are putting them at risk.

“So why has the Government ignored all the evidence and advice? Perhaps it is because of a misplaced belief that making sex and relationship education compulsory in free schools and academies would diminish their autonomy.

“I remember having a similar, fruitless argument in the last government with then Education Secretary Michael Gove about making careers advice and guidance compulsory — I was told then that it would offend the principle of school autonomy.”

But he continued: “The real reason, I fear, is [that] the Government simply doesn’t want to offend Conservative backbenchers and the Right-wing media, many of whom believe that talking to children about sex encourages a permissive, amoral attitude towards it.

“The Government has a duty to keep its citizens safe — and that is more important than ever when it comes to our children and young people. Ducking this issue may win them a few brownie points with the misguided moralisers but it is a dereliction of that duty.”

Writing for PinkNews previously, Education Select Committee chair Neil Carmichael insisted that “the most effective way of improving the sexual health of the nation is through education”, and that the government is “simply not doing enough” to push on the issue.

A Government spokesman told PinkNews: “Both Nicky [Morgan] and the Prime Minister believe it’s important that young people are properly prepared to succeed in modern Britain and schools have a key role to prepare them to do that. High quality PSHE is one way schools should be doing that.”