An unknown number of 14-year-old pupils have been wrongly registered as absent for their national curriculum tests in English, maths and science because of a computer error, the exams watchdog admitted yesterday.

The Qualifications and Curriculum Authority also said that one month after 600,000 Year 9 pupils were due to receive results from their Key Stage 3 tests, marking of papers was still going on across England. It added that urgent action was being taken to correct results that wrongly showed as being absent pupils who had taken the tests, known as SATs.

The problem emerged as Ed Balls, the Schools Secretary, confirmed that he would press ahead with the publication next week of headline national results for the secondary school tests. But he said that figures for individual councils will be delayed because the marking of papers could not be completed in time.

In English, 84 per cent of results are in, and 94 per cent of science and maths, as delays continue at the test contractor ETS.

Michael Gove, the Shadow Children's Secretary, said that the results published next week would be incomplete because the Government had failed to ensure that the testing process ran smoothly and on time.

“Ministers have let down parents, pupils, heads and teachers and there's still no sign that they appreciate their direct responsibility for the fiasco,” he said.

David Laws, the Liberal Democrat Shadow Children's Secretary, said that Mr Balls' announcement on Key Stage 3 results was a complete “dog's breakfast”. Ministers were too petrified to admit that there were serious questions about the accuracy of the Key Stage 3 results. “If the results are not now accurate enough to publish at a local authority level, they should have been held back at a national level too,” he said.

Children living in the most deprived parts of the country are 20 times more likely to go to a failing school than children in the wealthiest areas, an analysis of official data by the Conservatives suggests.

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