The Prime Minister intervened after a teaching union said its members were navigating a 'minefield' around gender.

He was asked about a report from a centre-right think tank Policy Exchange which looked at 154 English secondary schools.

It found only 39 of them reliably informed parents when pupils identified as trans or questioned their gender,

Eighty-seven schools found parents were not reliably informed, 14 did not provide enough detail and a further 14 chose not to respond.

The authors of the report, written as part of the think tank's Biology Matters Project, submitted a Freedom of Information (FOI) request to 304 of England's 24,000 secondary schools.

The schools were chosen at random. Any special schools which were selected were discounted from the report as Policy Exchange said "many of the issues raised are not applicable or relevant" to them.

Schools were asked a series of questions about their policies on issues ranging from whether schools would disclose to parents as soon as a pupil 'comes out' as transgender or questions their gender, to whether children should play in sports teams that don't match their sex registered at birth. Only 154 of 304 schools responded. Not all of the schools responded to all of the questions asked.

The report claimed some schools felt disclosing information to parents about whether a questioned their gender identity, or expressed a wish to change gender, would breach the child's confidentiality.

When asked about the report during a visit to the UK Atomic Energy Authority in Oxfordshire on Thursday, Mr Sunak said he was "very concerned."

He added: "For me, the safety and wellbeing of our children is of paramount importance. I've also been clear that parents must be able to know what is being taught to their kids in school, especially on these sensitive areas.

"I'm also going to say today that for the summer term we will make sure we publish guidance for schools so that they know how to respond when children are asking about their gender.

"These are really sensitive areas, it's important that we treat them sensitively, and that parents know what's going on, and we'll make sure that that happens."

The Teaching Union Association of School and College Leaders said schools had been waiting for guidance for "several years."

ASCL General Secretary Geoff Barton said: "Schools work very hard to be sensitive to the needs of pupils questioning their gender identity, and all their pupils, by providing a supportive and caring environment, and teaching children sensitively about respectful relationships in a diverse society through RSE lessons.

"Unfortunately, they are endeavouring to do this in the context of a public minefield of strongly held and opposing views, of which this report from a think-tank is yet another example.

"Meanwhile, the government has still not produced guidance for schools on supporting pupils who identify as trans or who are questioning their gender identity, despite this having been under discussion for several years.

"This is clearly needed so that schools are able to draw on an established set of guidelines rather than constantly being caught in the crossfire between opposing views and beliefs."

A Department for Education spokesperson said its priority was the safety and wellbeing of children and young people.

"The education secretary is working closely with the minister for women and equalities to produce guidance for schools, which we will be consulting on shortly.

"In the meantime, we are clear that schools should make sure they work with parents, pupils and public services to decide what is best for individual children."