Almost a thousand primary schools are failing to give their pupils a decent grounding in reading, writing and arithmetic, official figures suggest.
Newly published data shows that 962 primaries in England would be classed as failing under tough new targets announced by the Government last month.
The statistic comes in new primary school league tables, which also highlight the chaos caused by this year's boycott of national curriculum, or Sats, tests.
The new target, published in an education White Paper, said primaries will fall below the bar if fewer than 60% of their pupils reach Level 4 - the standard expected of the age group - in English and maths and fewer youngsters make two levels of progress in the subjects than the national average.
According to today's figures, the national average for English this year was 87% making two levels of progress and for maths it was 86%.
Those schools that fail to reach the target face closure or being taken over.
Today's primary school league tables show that 962 schools, out of around 11,500 for whom results are known, fail to meet this threshold. This figure will have been affected by the boycott.
Last year, 1,631 schools would have fallen below, the Department for Education said.
The target was introduced as part of a major overhaul of England's schools system, and Schools Minister Nick Gibb insisted today the new standards were "firm but fair".
He said the statistics show that many primaries are providing a "first-class education".
But he added: "Currently half of all 10 and 11-year-old boys who qualify for free school meals are being let down by our education system. It is unacceptable that after seven years of primary school these children are not at the standard in English and maths that they need to flourish at secondary school."
Ministers are focused on improving reading ability and raising behaviour standards, he said.
"It's why we are introducing new fair but firm floor standards to identify under-performing schools - but schools with challenging intakes won't be classified as under-performing if their pupils progress well, he added.
The primary school league tables show how every 11-year-old in England performed in English and maths tests.
Data for a quarter of schools, around 4,000 in total, is missing due to a boycott by two teaching unions, the National Union of Teachers (NUT) and the National Association of Headteachers (NAHT).
It means each table shows gaps in results for schools that did not sit the tests, which will make it harder for parents choosing schools for their children to compare the results of different primaries.
The tables reveal that slightly more primaries scored full marks than last year.
They suggest that 289 primaries succeeded in making sure every 11-year-old left with Level 4 in both English and maths, compared to 282 last year.
At just one school, Manuden Primary in Bishop's Stortford, every pupil scored a Level 5 - one above that expected of the age group - in both English and maths.
This school had the highest average points score.
Acting headteacher Pauline Gordon put the school's success down to excellent teachers and high expectations.
Two schools recorded 0% for the proportion of pupils gaining Level 4 in both English and maths.
One was Kingsfleet Primary School in Felixstowe, which recorded 0% for its English results but 84% for maths.
Headteacher Kirsty Beattie said the school's English results could not be published due to a discrepancy with the reading test.
She said: "I contacted the authority as I wasn't sure it had been a fair test, because the children were given about five minutes less than they should have been, due to the teacher mis-timing the test. I was asked to send off the papers to be marked.
"As it happens they did well in the test anyway, but it didn't sit with my conscience - I know there are strict guidelines and we wanted to follow them to the letter."
When the papers were marked, the school's English results were also 84%.
Mrs Beattie added: "They had made really good progress and it's unfortunate that, with the data as it is reported, you do not get a clear picture."
Starks Field primary school in Enfield, north London, got 0% for all its results.
Deputy leader of Enfield council Achilleas Georgiou said the results did not reflect the quality of the school.
"As the only children in the school taking Sats were 13 children that had joined the school just five months earlier, their league table position is a false one and does not reflect the quality of teaching in the school, which has been praised by Ofsted," he said.
The most improved school was Pilgrim School in Rochester, Kent, which has seen its average points score grow by 5.9 points since 2007.
Headteacher Jan Taylor said: "We really try to be adventurous with our learning, I think that's the real key."
Ilderton Primary School in south London added the most value to its pupils' education.
For the first time this year, results for science tests were not included, because they were scrapped by former Schools Secretary Ed Balls.
But teacher assessment figures for English and maths were included.
Figures published in August showed that across England, slightly more pupils were reaching the levels expected of them in the basics.
Some 81% of 11-year-olds reached Level 4 in English, up from 80% last year and 80% reached this level in maths, up from 79% in 2009.
Christine Blower, general secretary of the National Union of Teachers said: "This is a snapshot picture which does not tell us the whole story about children's performance. Level 4 was supposed to be the level that the average child achieved, not every child.
"The majority of these schools will be in the toughest areas where headteachers and teachers will have to be working very hard indeed to do the best for their pupils.
"Yet again, the case is made to end the demoralising naming and shaming process we have for assessing pupil progress. League tables and constantly changing, pointless floor-targets need to go and be replaced by properly moderated teacher assessment."
Read the Department for Education Primary School Tables here