The UK will be left out of a major international survey of education standards because the government did not provide enough information.
The survey will compare children's performance
The study - by the OECD
(Organisation for Economic Co-Operation and Development) is known as PISA.
It compares the performance of 15-year-olds in maths, literacy and science and comes out every three years.
Education Minister David Miliband said it was "disappointing". The Tories claim the data was suppressed.
The data supplied to the OECD comes through questionnaires answered by schools.
The organisation said not enough data came from England to make reliable comparisons.
Scotland and Northern Ireland carried out an independent sample that met the PISA requirements.
Their results will be featured individually in an annex to the report.
Wales did not participate as a separate country but intends to do so in the next round, in 2006.
Normally, the UK is grouped as a whole for the comparison.
School Standards Minister David Miliband said: "It is disappointing that data for the UK will not be fully reported on 7th December.
"We will look at the lessons from this study with a view to our full participation in the next study in 2006."
In the last PISA study, published in 2001, the UK was ranked above average in literacy, science and maths.
Then, the focus was on reading literacy. This time the main focus will be on maths.
In the UK, participation was co-ordinated by the Office for National Statistics.
The DfES said the data supplied fell short of the amount required under the "very strict technical requirements".
It said: "In 2003 the level of returns was below the OECD technical
"As a result, OECD have concluded that they cannot say with confidence that
the sample reliably reflects the national population with the level of accuracy
The government is facing criticism from teachers and its political opponents over the situation.
Steve Sinnott, general secretary of the National Union of Teachers, said there had been a "bit of a cock-up".
"The OECD PISA research is quite simply the most important international study of education," he said.
"It is a major disappointment that England should not be included in this report particularly since this country did so well in the last report."
Shadow Education Secretary Tim Collins said: "Given the negligible effort that the collation of these statistics would have involved, the government's lack of urgency is highly suspicious.
"It is not unreasonable to assume that the results would have made for unpleasant reading and have therefore been deliberately suppressed."
Phil Willis, the Liberal Democrats' Shadow Education Secretary said: "It is shocking that the government's failure to get its act together has led to the UK missing out of this essential assessment of our education system.
"International standards are becoming increasingly important and it is vital for ministers, teachers and pupils to know how we compare to our European neighbours."