Urgent action is needed to improve the standards of reading in under-performing primary schools, says the head of education watchdog Ofsted.
Reading has improved - but there is a hard core of under-achievement
There are 2,235 primary schools where a third of 11-year-old pupils do not reach the expected literacy levels.
While there have been overall improvements in reading, the Ofsted chief, David Bell, expressed his concerns about a "stubborn core" of weak schools.
"The lacklustre approach found in some schools is very worrying," he said.
Mr Bell, the chief inspector for schools in England, presented a report - Reading for Purpose and Pleasure - that showed a sustained overall raising of reading standards.
The focus on raising literacy standards in primary schools - under the "national literacy strategy" - had brought success, with English primary school pupils among the best readers in the developed world, he said.
But Mr Bell said he was very concerned at the growing gap between these improving schools and a group of unsuccessful schools which persistently under-achieved.
"The continual under-performance in reading standards achieved by pupils in some schools must no longer be acceptable," said the chief inspector.
Inspectors would be demanding action plans from ineffective schools, said Mr Bell - and specialist support should be available for teachers.
"We're making the point that this really, really matters for these chidren - and we can't just allow schools to drift on," Mr Bell told reporters.
If schools failed to intervene with struggling readers in primary school, these pupils were likely to be condemned to failure in secondary school.
Learning to read was the "cornerstone" of children's education, he said.
'Nail the myth'
Mr Bell also said that he wanted to "nail the myth that it's all to do with the background of the children".
"It is simply not good enough for some schools to lay the blame for low reading standards on the children, parents or outside influences."
There were plenty of examples of schools with a deprived intake who were successfully learning to read and "raising expectations", he said.
And he rejected as "bunkum" the suggestion that the literacy strategy was too restrictive and could be reducing children's appetite for reading for pleasure.
"You can't acquire a love of books if you can't read," he said.
Mr Bell pointed to the links between schools with high standards in reading and the successful use of "phonics" as a teaching technique.
An effective head teacher, giving leadership over reading standards, was also a key factor in successful schools, he said.
Mr Bell also expressed fears about schools which allowed the growth of computers and information techology to reduce the traditional role of the school library - or where computer use was at the expense of books.
In response, the Schools Minister, Stephen Twigg, said the report recognised rising standards .
He said that since 1997, the proportion of 11 year olds reaching the expected literacy levels had risen from 67% to 83%.
The number of schools where fewer than 65% of pupils achieved these expected levels had fallen from 6,100 to the current 2,235, said Mr Twigg. There are currently about 17,800 primary schools in England.
The Shadow Education Secretary, Tim Collins, said: "For a government that promised so much for education in general and literacy in particular, this report makes for dismal reading."
Steve Sinnott, general secretary of the National Union of Teachers, welcomed the report as a "recognition that the teaching of reading is a success story. Schools have committed enormous time and energy in ensuring pupils' reading develops to the highest level".