Headteacher Robert Underwood ordered the closures at Hardley school in Holbury, near Southampton, to give his staff “some respite” from “exceptional workloads”.

Despite timetable changes, temporary appointments and the use of supply staff, the main burden has fallen on colleagues “working way beyond the terms of their contract” by covering additional classes and holding lessons after school, he has told parents.

Most pupils will lose 10 hours teaching (eight hours for GCSE students), while their teachers will be in school catching up on professional tasks.

In Leicester, nearly 1,000 pupils will get two days extra holiday at Christmas because teachers say they are owed time after covering for sick colleagues.

In a letter to parents, David Mclean, head of the English Martyrs RC secondary, said: “This earlier-than-planned finish is the result of the effects of national action by the main teacher unions in their dispute with the Government over contract and workload issues.

“In particular it is because new restrictions on matters of cover for absent staff means that absences can be totalled, and teachers may then have time off in lieu.”

The school will close on the Wednesday before Christmas instead of the Friday. Mr Mclean added:“I hope that the union dispute with the Government can be resolved in the spring.”

Jane Rolfe, the Leicester National Union of Teachers’ spokeswoman, said the school was simply following good practice agreed by employers and unions.

The agreement to give time back to teachers who covered for absent colleagues was reached in September after staff refused to use non-contact time to provide cover.

A Department of Education and Skills spokeswoman said schools were free to decide how lessons are arranged in the week - as long as they meet the statutory requirement to provide 380 sessions (190 days) during the academic year.

“Hardley’s governors and the head have reorganised their timetable in a way that makes best use of the schools’ resources.”