Ministers have hailed "record results" in England's primary schools, but have criticised five schools which cheated in the exams.

Schools minister Lord Adonis said on Thursday that "standards in our primary schools have never been higher".

But it also emerged that four schools saw their results invalidated in English, maths and science, while a fifth was stripped of its English results.

National Association of Head Teachers general secretary Mick Brookes said news of malpractice was "deeply sad".

He added that it "demonstrates the extreme pressure that some schools and some teachers feel to perform to targets which may not reflect the ability of the children".

"We need an assessment system that promotes professional integrity and this one does not," said Brookes.

For the government, Lord Adonis said it was "unacceptable and unnecessary for any school or teacher to cheat".

"Clearly, five out of over 13,000 primary schools is not at all representative of what is happening in our schools and cannot be seen as any indication of national tests causing increased pressure on teachers," he said.

"Most members of the teaching profession think that parents have a right to see how their school performs in comparison to other schools.

"These accountability measures are essential to maintaining and extending the improvement in standards we have already achieved."

The national results showed that 80 per cent of 11-year-olds achieved the target in English, a rise of 17 per cent since 1997.

In maths some 77 per cent achieved the target level, up 15 per cent, while in science the proportion reaching the required level rose by 19 per cent to 88 per cent.

"Tribute for today's record results must go to pupils and teachers, standards in our primary schools have never been higher," said Lord Adonis.

"Compared to 1997, 100,000 more 11-year-olds are mastering the basics in reading, writing and arithmetic."

He pledged continued support for children struggling with literacy and numeracy, and said there would also be greater emphasis on phonics in early reading teaching while in maths there will be more mental arithmetic.