Schools may be breaking the law by letting pupils stay at home on academic-review days, according to the Government. Secondary heads are in dispute with ministers and the Department for Children, Schools and Families about the legal requirement for pupils to be in school for 190 days per year.

Whitehall is also concerned about children skipping key stage 3 tests. It has imposed a new duty on schools to explain high absence rates. But secondary heads see the intervention as meddling, suggesting that the tests are a waste of time.

The Association of School and College Leaders (ASCL), which represents many secondary heads, estimates that around a quarter of schools run one or more review days per year, sending classes home so teachers can meet pupils and parents by family to discuss their performance targets.

This allows form tutors and families to set personalised objectives for the pupils, which take more time than can be allotted in traditional parent-teacher evenings. Official guidance says that the day out from classes means schools are delivering only 189 days’ teaching a year, in breach of regulations. “We would wish schools to discontinue any such days,” the guidance says.

John Dunford, general secretary of the ASCL, has written to Jim Knight, the schools minister, to say such days make a substantial contribution to raising achievement.

“Academic review days are a creative response by schools to the exhortation by ministers to engage in such activities,” he said. “It would be deeply ironic if it is the Government that brings them to an end by the mechanistic application of rules on registration and attendance.”

Mr Dunford will press his point further this week with Ed Balls when the Schools Secretary attends the association’s annual conference in Brighton.

Jane Lees, headteacher of Hindley Community High School Arts College in Wigan, Lancashire, has been closing her school two days a year for the past three years to hold review days.

“I do understand what the Government is saying, but they are asking us to set personalised targets and these days allow teachers to spend 15 minutes of quality time with pupils and parents, who really value it,” she said. “We know that it has had a positive impact on performance in the school and for the Government to say we can’t do this is just micromanagement.” Mrs Lees objected to Mr Knight’s suggestion that schools cram the review days into evening sessions as they put too much pressure on staff and do not allow enough time.

She also dismissed other official suggestions, such as keeping pupils busy with supply teachers, teaching assistants or non-teaching pupil mentors. “It is better to send pupils home to carry on with tasks than involve them in a time-filling exercise at school,” she said.

“And supply teachers are expensive.”

Brian Lightman, the ASCL president, will use his conference speech to criticise the requirement to report key stage 3 test absences as “time-wasting bureaucracy that benefits no one but civil servants”.

Heads have also been taken to task about children skipping key stage 3 tests after officials pointed out that while absence rates for key stage 2 tests are 1 per cent, for key stage 3 it is around 3 or 4 per cent.

Mr Lightman will say: “For a government that has said it wants to give schools more autonomy, this is a disappointing backwards step.”