Investigations are to take place to find out why some pupils who receive free school meals are underperforming in their exams.
Ofsted inspectors are to visit schools in Northumberland to find out why the attainment for children who are eligible for free school meals (FSM) is well below other youngsters in the county, north east region and nationally.
In 2012, only 61 per cent of children on FSM achieved Level 4 in English and maths at Key Stage 2, compared to 82 per cent of their non-FSM peers in the authority, while children between Key Stage 1 and 2 in Northumberland made the least progress of all local authorities in the north east in English and maths.
But the situation is worse in secondary schools, with only 26 per cent of pupils on FSM achieving five or more A* to C GCSE grades including English and maths compared to 62 per cent for other pupils in the county.
And Ofsted data from August shows that 37 per cent of secondary schools – including middle deemed secondary – were judged less than good at their last inspection.
It means that Ofsted officials have moved forward inspections to address the issue.
Nick Hudson, regional director for the north east and Yorkshire and Humber, said: “While I recognise that primary schools in Northumberland are doing well, I am very concerned that children on free school meals in the county are not getting the education they deserve.
“The proportion of children on free school meals in the county is relatively low and therefore it is even more of a worry that there is a significant attainment gap for these children compared to their peers.
“This is an unacceptable situation.
“Inspectors will be visiting a number of schools in Northumberland to find out why the pupil premium is not being effectively used to help disadvantaged children, as well as examine the underperformance of secondary schools.
“We will be paying particular attention to the effectiveness and impact of the support these schools are receiving from the local authority.
“Children only get one chance of an education.”
A Northumberland County Council spokesperson said: “We understand the challenges and we’re committed to achieving the best for all our students and supporting our schools to provide a high quality education.
“We were delighted to welcome David Laws, minister of education, to Northumberland earlier this year to discuss the performance gap of pupil premium pupils.
“Recently headteachers and chairs of governors of all our schools currently judged satisfactory attended a conference run by Ofsted in Northumberland on ‘getting to good’.
“Northumberland has some significant challenges, low funding levels, a range of educational structures and the challenge of sparse rural populations. We will use the findings of these inspections to review and improve the support we provide to schools.”