A headteacher has demanded the Government "repairs the damage" it caused her school after publicly labelling it underachieving.

In a letter to Prime Minister Gordon Brown, Ravenscroft School headteacher Mary Karaolis said she was "appalled and insulted" at the Government's "headline grabbing" approach to school reform.

The searing attack comes after Education Secretary Ed Balls targeted 638 UK schools for additional support and funding as part of the Government's National Challenge initiative.

Last year fewer than 30 per cent of pupils at these schools achieved five grades A* to C at GCSE, including maths and English.

But Mrs Karaolis, whose school in Barnet Lane, Whetstone, achieved 29 per cent, believes targeting Ravenscroft in this way was "unfair". She pointed out that it achieved an outstanding Ofsted report earlier this year and has one of the highest contextual value-added (CVA) scores in the country, which measures pupils' progress from year to year.

She said: "This announcement we consider to be very unfair on a challenging school such as ours. We do not have a balanced, comprehensive intake in terms of ability, and our CVA score of 1,028 and our recent outstanding Ofsted report are indications of the success of our school.

"I would have expected the Government to have been more thorough in its knowledge of schools and interpretation of data. It should be directing its attention to underperforming schools which have negative CVA; those are the schools that are failing the children.

"I would like to know how the Government intends to repair the damage inflicted on the reputation of my school in the wider community and the negative impact that the failure' list has had on the morale and self-esteem of our school community of students, staff, parents and governors."

A spokesman for the Department of Children, Schools and Families stressed that the Goverment had not published a list, but only pledged to spend £400 million on schools failing to reach the 30 per cent target.

However, Government figures showing school performance are publicly available.

The spokesman added: "There will be universal support for National Challenge schools below 30 per cent, including an adviser for each one. These advisers will support the school directly, and broker additional support tailored to the school's needs.

"We make no apology for having high ambitions - all children deserve the opportunity to achieve. We know many schools in the National Challenge are already doing good things, which some schools with higher results might not be doing."

Theresa Villiers, Conservative MP for Chipping Barnet, dismissed the Government initiative as "ill-judged". In a letter to Mr Balls, she said: "Along with the governors, Mary Karaolis and her staff have spent many years working incredibly hard to improve the educational opportunities Ravenscroft offers.

"Your ill-judged criticism will have undermined much of the careful work done over recent years to build confidence in the school among parents in the area.

"Even worse, you will have dealt a blow to the confidence of Ravenscroft's students, who have been working so hard to pass their exams and achieve their potential, and many of whom have to contend with difficult family and personal circumstances."