The Government has been criticised after it failed to produce data on English schools for the most respected international comparison of education standards.
England will be the only developed country to be excluded from the Paris-based Organisation for Economic Co-operation and Development's study of 15-year-olds' performance after the Government failed to ensure sufficient schools and pupils took part.
Andreas Schleicher, head of indicators and analysis at the OECD, said:
"More could have been done to encourage schools' participation."
Other countries, notably the Netherlands, who had been warned about their data had launched campaigns to convince schools of the benefits of taking part, he said.
The decision will be seen as an embarrassment for ministers, particularly as they made great play of the first Programme for International Student Assessment (Pisa) report on literacy, published three years ago, which suggested that English schools were among the best in the world.
Critics accused the Government of being content to drop out of the study because of fears that England would have fared badly in this year's report.
One academic said: "Ministers made a lot of the 2000 results, even though they were out of line with previous international studies, because the figures told them what they wanted to hear. This year they have been quiet and this confirms why."
But Mr Schleicher dismissed suggestions that the Government had deliberately failed to collect sufficient data or opted not to be included in order to downplay disappointing results.
The decision to exclude England was taken to protect the reputation of the study, he said.
Only two-thirds of English schools selected took part in the OECD's study, compared to a requirement of 85 per cent. Mr Schleicher said the bigger problem was that, even in participating schools, only 77.9 per cent of pupils took part. The OECD average for pupil participation was 89.5 per cent.
Mr Schleicher said he did not know why so few pupils had taken part, but said that schools may have been trying to boost results by allowing less able pupils to miss the test.
John Bangs, National Union of Teachers head of education, described the problems as a major shock.
David Miliband, schools minister, admitted that England's exclusion was "disappointing".
A Department for Education and Skills spokesman said that secondary schools are more reluctant than primaries to take part in international studies but ruled out following the lead of other countries and compelling them to do so.
England's results will be in the report, which will focus on maths and be published next month, but they will not be compared with those of other countries.
Results for students in Scotland and Northern Ireland do meet the required standard and will be published as part of the comparisons. Data on Wales was not collected separately.