Primary schools in England asked for a remarking of this year's English test for more than 5,000 pupils, amid concerns about the validity of the results.

Some schools say the marked gap between the apparent reading ability and writing skill of the same sets of 11 year olds suggests there is something wrong with the writing test.

Figures released on Wednesday show that in the national curriculum tests sat in May, 75% of 11 year olds reached the expected level in English for their age group - an improvement of 10 percentage points since 1998.

But that overall figure masks a split between reading, on 83%, and writing, on only 55%, albeit slightly better than last year.

Head teachers belonging to the National Primary Heads Association are suspicious.

Appeals figures

Spokesman Chris Davis claims there were "obvious errors" in the marking of the writing test.

The Qualifications and Curriculum Authority (QCA), which oversees the setting and marking, refutes this.

Figures released to BBC News Online on Wednesday show there were 5,473 "requests for review" from schools, asking for checks on the quality of marking of pupils' English tests, up from 4,974 last year, when there were similar concerns.

This is only a tiny proportion of the total papers sat by pupils - about 1% - but is far more than in the other two subjects tested, maths (593 appeals) and science (976), where answers are much more clearly right or wrong.

The overall outcome of the reviews is not yet known.

Ofsted blamed teachers

Chris Davis says that in his own primary school in Queniborough, Leicestershire, almost all the pupils - 94.5% - achieved the standard expected for their age in the reading test - but only 33.4% in the writing test.

The school asked for almost two thirds of the writing test papers to be reviewed - and the result went up 23%.

The schools inspectorate, Ofsted, looked into the issue last year and, in a report in December, said more attention should be given to training teachers to teach writing effectively.

The worry for schools is that, following that report, many of them had made an extra effort ahead of this year's tests - with very little result.

Chris Davis said: "The results that the children are achieving are actually far higher than is being reported.

"Writing is the most problematic subject to mark. Most of the other subjects are fairly straightforward.

"With writing the marker has to read the piece of work very carefully indeed, compare it against the criteria which are established in the marking scheme, and it's quite a long job to do it accurately."

The "gender gap" is even more worrying for ministers, with 63% of girls hitting the expected level in writing but only 48% of boys.

In other words, fewer than half of England's 11 year old boys can write as well as they ought to be able to.

New grammar guide

The government's response is to give teachers extra training in teaching writing.

The Education Secretary, David Blunkett, is allocating �9m for special courses for teachers of nine and 10 year olds.

Schools are also getting a new guide, Grammar for Writing, from the National Literacy and Numeracy Centre.

"What's been shown to work over the two years that we have seen this enormous uplift in literacy and numeracy ... it's been the teaching methodology, it's been the teaching materials and the in-service training," Mr Blunkett said on BBC Radio 4's Today programme.

"We've got an enormous problem in terms of engaging young men with the importance and love of being able to write well."