An Ofsted report into Norfolk County Council's children's services department has found that the authority is 'ineffective' in supporting the county's schools.

Inspectors visited County Hall last month in the first two inspections of their kind in the country, to analyse how the council challenges and supports schools to improve.

But the county council has today pledged to strengthen its strategy to support school improvement, saying the verdict was 'no surprise'.

Inspectors said that the council's new strategy for supporting school improvement, A Good School for Every Norfolk Learner, was a 'clear statement of intent to challenge and support schools to improve.' However, at the time of the inspection the strategy had not yet made a strong enough impact and inspectors found it lacked clear targets for the county's schools.

Gordon Boyd, assistant director of children's services at Norfolk County Council, said: 'We have too many schools in Norfolk that are not good enough or have not been quick enough to improve. Ofsted's judgement, therefore, comes as no surprise and highlights our clear role in ensuring that schools are supported and challenged in their own improvement.

'In the past we have been too slow to act in schools that are causing concern. However, our new strategy focuses on much earlier intervention and is beginning to show positive signs of progress – the proportion of good and outstanding schools in the county is increasing and the role of the council in supporting school improvement has been found by Ofsted to be effective in the vast majority of recent school inspections.

'Despite this we realise that there is a long way to go. Norfolk is behind the national average at both GCSE and Key Stage 2 and we need to challenge schools more robustly if they are not providing the good education their pupils deserve.'

Ofsted said that the impact of local authority intervention was improving and more schools had become receptive to challenge and support. However, a significant minority of schools remained ambivalent or resistant to partnership working and inspectors said this was 'slowing the pace of improvement.'

Mick Castle, cabinet member for schools at Norfolk County Council, added: 'The county council has previously seen cuts in this area and that is something we are keen to address. Improving services to children and young people in Norfolk is an absolute priority for this administration and that is why we recognise that the outcome of this inspection is simply not good enough.'

'We have just appointed Sheila Lock to lead children's services in the interim [following the departure of previous director Lisa Christensen] and we know she has a strong track record of bringing about improvements in both education and social care. We are confident that she will provide further support to our strategy to support school improvement and ensure we, and the council's schools, are making the rapid progress that is necessary.'

Norfolk County Council has already shared its strategy for supporting school improvement with colleagues at other high-performing local authorities and schools.