Thousands of pupils are leaving primary school unable to read because of lacklustre teaching, David Bell, chief inspector has said.
In a critical report about the teaching of reading in primary schools, Mr Bell said teachers often blamed parents for pupils' low achievement. He expressed concern at the continuing gulf in attainment between schools in similar circumstances, and said up to 2,500 primaries were not doing as well as they should.
Many schools, he said, did not encourage children to read for pleasure.
The Office for Standards in Education report casts doubt on the use of classroom assistants to teach reading. "Assistants often worked with some of the most challenging groups... However, they did not always have the confidence and knowledge about teaching reading to adapt intervention programmes where it was necessary," it said.
Mr Bell, whose inspectors visited a sample of 45 schools, blamed a lack of decisive leadership by headteachers who did not know enough about teaching reading, and recommended greater intervention in schools where literacy standards were consistently low.
"It is unacceptable that too many children do not learn to read properly because the adults who teach them lack sufficient knowledge to do so effectively. This might have been understandable a decade ago, but not today," he said.
The report, Reading for purpose and pleasure, found that the most successful schools identified pupils' difficulties early.
But in unsuccessful schools, there was a "lacklustre approach" and "one intervention programme followed another with too little evaluation of their appropriateness and impact".
Children in some schools failed to make enough progress because teachers had low expectations of their ability to learn phonic knowledge and skills.
Guided reading was unsatisfactory in a third of lessons in poorly performing schools, because "many teachers did not understand its principles and struggled to teach it successfully".
Inspectors observed that in some schools children were left to guess words from a picture in a book because they had not been taught how to decode a word phonetically.
Competent readers were sometimes held back. One child said she had to wait a week after finishing a book to choose a new one. Other were given books to read instead of being allowed to choose something that interested them.
Mr Bell said such examples meant that children often did not enjoy reading.
Even those who read well seldom did so for pleasure.
He said few schools were successfully engaging the interest of those who, though competent readers, did not read for pleasure.
"Schools seldom build on pupils' own reading interests and the range of reading material they read in schools," he said.
Unsuccessful schools, Mr Bell added, "were often hindered by a culture of low expectation. They failed to examine their own practice critically enough, often blaming others for pupils' low achievement".
Mr Bell said: "The findings are unacceptable. A stubborn core of pupils at the bottom end of the scale are being let down by the system."
But critics of government policy have suggested there is little time for teachers to enthuse pupils as they struggle to hit targets. Children's author, Vivian French, who goes into schools to help with reading, said:"I have to say 'poor old teachers'. They must be losing the will to live with the weight of expectations and the targets."
Michael Morpurgo, the Children's laureate, and author of Wombat Goes Walkabout and The Butterfly Lion said: "While books are used simply as tools for testing and asking pupils questions then you will never enthuse children to read.
"Half an hour a day should be set aside in schools for stories, either writing them, listening to them or reading them. When children see that teachers love reading, they might begin to as well."
Stephen Twigg, the education minister, said: "We know there is a tail of underachievement. We will continue to build on the success of the primary strategy to address the concerns Ofsted raises to ensure schools have the necessary support to improve further."
John Coe, of the National Association for Primary Education, said the tests and league tables led to coaching and "sadly, a relative neglect of children with more serious needs".
Shadow education secretary Tim Collins said the report made dismal reading.
He said: "When will ministers realise that the arbitrary setting of targets for reading and writing is just not the answer? Primary heads want the freedom to be able to tailor their literacy teaching to address their children's needs."
The report is available at www.ofsted.gov.uk or telephone 07002 637833.