An investigation has found that cheating in SATs for 11-year-olds is so widespread that school league tables can no longer be trusted.

The Guardian questions whether the former education secretary, Estelle Morris, would have faced a crisis of confidence among parents and teachers had she stayed on until next month's publication of primary school league tables.

Forum Response: Association of Teachers and Lecturers

Gwen Evans, deputy general secretary for ATL, told ePolitix.com: "It's a great pity these unsubstantiated rumours have surfaced again. The real problem with SATs is that their existence overshadows Year 6 pupils' lives, as they are heavily prepared, with weeks of revision and coaching.

"It's time for a government re-think. If they sincerely want standards to rise they must question their unthinking reliance on external tests before it's too late."

Forum Response: National Union of Teachers

A spokeswoman for the NUT told ePolitix.com: "Tampering with test results or cheating in tests is extremely unacceptable. The government has placed enormous pressure on schools test and examination systems.

"It has long been believed that a review of the test system should be carried out and the NUT hopes the new education secretary will do this."