More than a third of primary schools in England are failing to perform to a controversial set of standards, according to figures uncovered by The TES.
Around 6,000 primaries - out of an estimated 17,000 - are struggling with low results or failing to make sufficient progress under criteria for the World Class Primary Programme.
The initiative is based on the hugely contentious National Challenge scheme for secondaries and is designed to aid school improvement.
Its main focus is on primary schools where fewer than 55 per cent of children achieve the expected Level 4 in both English and maths at the end of key stage 2 (age 11). But it also covers schools that are deemed inadequate by the Ofsted inspectorate, have inconsistent results or are coasting.
The Government has published statistics showing that 1,472 primaries are under the 55 per cent floor target. It has also been made public that around 300 primaries are either in special measures or have a notice to improve from Ofsted.
But previously unpublished figures - which feature in National Strategies presentations to local authorities - show that in addition to these schools, approximately 3,400 are deemed to be coasting and 1,000 to have inconsistent results.
Just 7,700 primary schools are good or outstanding, according to the National Strategies figures. Their estimates do not include the performance of a further 3,200 schools, meaning that the total could be even higher.
The World Class Primary Programme was launched at the end of last year, with pound;50 million to be invested in school improvement partners and specialist teachers.
Mick Brookes, general secretary of the National Association of Head Teachers, criticised the high number of schools identified as needing to improve.
"It assumes that one-third of schools have headteachers and staff going into schools determined not to improve children's education," he said. "That is just complete science fiction.
"This is the wrong way to encourage schools and the children in them. It makes them feel disempowered, bullied, harassed."
The National Challenge scheme for secondary schools is aimed at schools where fewer than 30 per cent of pupils achieved five good GCSEs, including English and maths.