There is no hard evidence that schools in England are slipping behind other countries, says an academic study.
Ministers have cited a decline in international league tables as a reason for introducing school reforms.
But the results of international tests are not consistent, says John Jerrim from the Institute of Education.
However, a Department for Education spokesman said it was clear "that our relative performance internationally has declined".
Head teachers called for the study to be considered seriously, saying that international comparisons needed to be accompanied by a "large health warning".
"Misleading comparisons and alarmist sound bites about us plummeting down league tables do the teaching profession a great disservice and undermine public confidence in our good and improving education service," said Brian Lightman, general secretary of the ASCL head teachers' union.
Rise and fall
The analysis by Dr Jerrim challenges the government's argument that England's schools have been overtaken by other countries and that radical change is needed to help them to catch up.
Dr Jerrim says that while the results of the previous Pisa tests have shown a fall in England's ranking, there are other tests, such as the TIMSS tests, in which England's schools have shown an improved performance.
A lot of weight is being put on one particular study," he says.
The Pisa tests - the Programme for International Student Assessment - are supervised by the Organisation for Economic Co-operation and Development and taken every three years in maths, science and reading.
The most recent results showed England's performance slipping down for all three subjects between 2000 and 2009, from 8th to 27th in maths, 7th to 25th in reading and 4th to 16th in science.
But Dr Jerrim says that a range of international test results show contradictory outcomes - and that it remained uncertain whether England was rising and falling.
"We can't say for sure that standards have been going up - or that they have been going down," says Dr Jerrim.
Prime Minister David Cameron and Deputy Prime Minister Nick Clegg, introducing their reform of England's schools, singled out England's declining performance in Pisa tests as a prime argument for change.
"The truth is, at the moment we are standing still while others race past," they wrote, introducing their government's Schools White Paper earlier this year.
But Dr Jerrim says that changes in relative international performance of schools is much more ambiguous than it appears.
The fall in England's ranking in Pisa tests was influenced by how the tests were conducted, as much as the ability of the 15-year-old pupils, he says.
There were different countries participating in different years - and he calculates that as much as half the apparent decline in England's performance could be because weaker schools had opted out of tests in previous years, inflating the earlier results.
However Dr Jerrim says even though he remains unconvinced by the evidence of fluctuations in ranking positions, there are clear differences in how well pupils perform in different countries.
By any measure, England's schools are behind a group of top-performing countries and school systems, he says.
The rankings from Pisa test results are headed by countries and regional school systems such as South Korea, Hong Kong, Shanghai, Singapore, Japan and Finland.
But below this group of highest achieving countries, he argues that there are many other countries which are "bunched" and where differences in performance are uncertain.
England is included in this group, he says, along with countries such as the United States, Australia and Italy.
Labour's education spokesman, Stephen Twigg, said; "David Cameron and Michael Gove should stop talking down our hard-working pupils.
"The selective use of statistics to support a dogmatic approach to education structures is wrong-headed. We need an evidence-based not an ideological approach to education reform."
But the Department for Education highlighted the scale of the decline in England's performance in Pisa tests and said that international authorities accepted its findings.
"We need to equip young people with the skills and knowledge that employers and universities need to compete internationally," said a Department for Education spokesman.
"Many other countries are improving their schools faster than we are and have much smaller gaps between the achievements of rich and poor than we do."