A head teacher is refusing to publish the results of some national curriculum tests after discovering such poor marking that pupils who performed strongly fared worse than poor students.

Janis Burdin, a primary school head in Chorley, Lancashire, described the marking in numerous instances as “absolutely off the radar”. She said that the children’s grades would not be published until the papers were remarked.

An 11-year-old child who had performed much better than a classmate in the Key Stage 2 English test was marked lower.

Child A wrote about Pip Davenport, a fairground inventor: “If he wasent doing enthing els heel help his uncle Herry at the funfair during the day. And had stoody at nigh on other thing he did was invent new rides.

“Becoues he invented a lot of new rides he won a prize. He didn’t live with his mum he lived with his wife.”

This received one mark more than Child B who wrote: “Quickly, it became apparent that Pip was a fantastic rider: a complete natural. But it was his love of horses that led to a tragic accident. An accident that would change his life forever.

“At the age of 7, he was training for a local competition when his horse, Mandy, swerved sideways unexpectedly, throwing Pip on to the ground, paralysed.”

Both children were awarded five out of eight for sentence structure. Child A was given eight out of twelve for composition and effect while Child B received only seven marks.

Ms Burdin, the head teacher of Moss Side Primary School, said: “These two papers were both given Level 4. I would have given one a 5 and one a 3. These are the most extreme differences but there are many more discrepancies. The marking, especially for the writing exams, is absolutely off the radar.”

The concerns emerged as Ed Balls, the Schools Secretary, was questioned by a committee of MPs about the administrative fiasco that has delayed the results of national tests for millions of schoolchildren. The serious concerns about the accuracy of marking could prompt thousands of appeals. Mr Balls refused to apologise when he appeared before the Children, Schools and Families Select Committee yesterday. He would say only that the situation was unacceptable and he was upset at what had happened.

The American contractor ETS Europe failed to have results of this year’s national tests for 11 and 14-year-olds ready for publication on time.

ETS, which is being paid £165 million over five years to manage the Key Stage 2 and 3 tests, has faced a barrage of complaints from parents, teachers and markers. The results are being returned at least a week late. Those ringing ETS to complain have been unable to get through, and e-mails have gone unanswered.

Barry Sheerman, the chairman of the committee, said that ETS was using some markers who had only recently passed their A levels. He told of one recent graduate who was the most experienced person on his marking team.

Douglas Carswell, the Conservative MP for Harwich, told Mr Balls: “When your predecessor, Estelle Morris, quit when she realised the QCA had made a cockup over testing, I seem to remember she found the humility to say sorry. Will you be saying sorry?”

Mr Balls said: “I don’t think that’s a correct description of what happened with Estelle Morris. What I’ve said is that it’s unacceptable.” Challenged again to apologise, he said: “I’m really upset, like you, about what’s happened and that’s why I’m having an inquiry.”

The hearing coincided with the publication of the terms of reference of an independent inquiry headed by Lord Sutherland of Houndwood into how the QCA has managed its responsibilities. Of the nine areas it will focus on, only one mentions the Department for Children, Schools and Families, asking whether it monitored QCA’s delivery appropriately.

Explore Education

• Sunday Times University Guide

• Good University Guide

• Schools

• Student

• GCSE & A Level Results

• Young Times

Times recommends

• Private schools face 'public benefit' test
• New teaching style gives pupils wake-up call
• Independent schools fail special needs pupils