The stark warning came as Children's Secretary Ed Balls announced the National Challenge, a £400 million rescue package targeting under-performing schools, where fewer than 30 per cent of students achieved five or more A* to C GCSEs – including English and maths – in their exam results last year.

Within the town, Kingsthorpe College, Mereway Community College, Northampton Academy, Unity College and Weston Favell School will fall under scrutiny after failing to meet the Government's benchmark.

They will be told to raise standards by 2011 otherwise they will be replaced by academies or National Challenge Trust schools.

Judith Long, principal of Kingsthorpe College and chairman of Northampton's Secondary Heads Group, said: "Nobody is complacent and we are all striving to improve in these key indicators. It is one of many ways in how a school is judged. The town's schools are confident we will achieve more than the 30 per cent target for GCSEs this summer."

Northamptonshire County Councillor Joan Kirkbride (Con, Bugbrooke), cabinet member for children and young people, said she welcomed the programme with caution. She said: "We welcome the National Challenge if it means support for schools with increased resources and targeted assistance, but if the National Challenge turns out to be a naming and shaming exercise – only without the promised extra funding – it will not improve school standards and the life changes of the children in those schools.

"In view of the history of government funding in Northamptonshire, the residents of our county can be excused for being sceptical about yet another government initiative."

A total of nine county schools will be under the Government spotlight. The others are Corby Community College, Ise Community College in Kettering, Kingswood School in Corby and Weavers School in Wellingborough.

They, along with more than 600 schools identified by the Government, will be allocated troubleshooters in the form of a National Challenger Adviser and receive mentoring from experienced heads.

Gordon White, county secretary for the National Union of Teachers, said: "I see this as a political gimmick rather than the measures having any substance. Yet again this is another knee-jerk reaction from the Government.

"These are schools in areas experiencing social-economical problems and will need time to improve. We feel this is an initiative to privatise even more state schools."

Special report in today's Chronicle & Echo