The publication of transgender guidance for schools will be delayed to allow more time to ensure it meets the “high expectations” of teachers and parents, the Government has said.

Education Secretary Gillian Keegan confirmed the long-awaited guidance would not be published as had originally been promised in time for schools breaking up for summer.

Following reports of the delay earlier this week, headteachers vented their frustration, branding the lack of guidance “frustrating” as teachers are having to navigate the “complex and sensitive subject” of gender identity on their own.

In an update as Parliament prepared to break for recess on Thursday, Ms Keegan said the Government is taking the issue seriously and added that “decisions must not be taken lightly or in haste”.

In a written statement, she said: “It is vital that the guidance we publish gives clarity for schools and colleges and reassurance for parents. So, we have made the decision to allow more time – to speak to teachers, parents, lawyers and other stakeholders – in order to ensure this guidance meets the high expectations that these groups rightly have for it.”

She appealed to schools and colleges to “proceed with extreme caution” in the intervening period, saying they “should always involve parents in decisions relating to their child, and should not agree to any changes that they are not absolutely confident are in the best interests of that child and their peers”.

She added: “They should prioritise safeguarding by meeting their existing legal duties to protect single-sex spaces and maintain safety and fairness in single-sex sport.

“I want to give reassurance of how seriously we are taking this issue, and will endeavour to keep the House updated ahead of any developments.”

The government must ensure that at the latest this draft guidance is ready when schools return in September so we don’t face yet another year of this ongoing debate

In March, Prime Minister Rishi Sunak pledged that guidance for schools on transgender issues would be published “for the summer term”.

Paul Whiteman, general secretary at school leaders’ union NAHT, said the delay was “deeply disappointing”, suggesting it was “seemingly due to internal government disputes”.

He said: “Schools need clarity on this situation to help them navigate sometimes difficult issues and ensure that all pupils are treated with respect, consideration and in accordance with the law.

“The government must ensure that at the latest this draft guidance is ready when schools return in September so we don’t face yet another year of this ongoing debate. We must remember that it is ultimately children and young people at the centre of this.”

Reports in The Times newspaper had suggested the Attorney General and Government lawyers said plans to strengthen guidance would be unlawful, leading to the delay.

Mr Sunak told broadcasters on Wednesday: “This is a really complex and sensitive issue because it affects the well-being of our children.

“And it’s important that we get it right, given those complexities and sensitivities.

“I’m committed to bringing forward that guidance but I want to make sure that we take the time to go through it properly.”

The Prime Minister’s official spokesman said on Thursday that the Government wanted to ensure the guidance “places the well-being and safety of children at its heart and that it makes sure that parents are always the ones that have the first say”.

But Downing Street could not say whether the guidance would definitely be published this year.

Geoff Barton, general secretary of the Association of School and College Leaders (ASCL) union, said: “Clear, practical guidance on this matter is important as long as it is genuinely supportive to schools and pupils and does not add to the existing and onerous expectations on schools.”