Education chiefs have vowed flagship reforms in Suffolk “will work” after poor primary school results saw the county again named as one of the worst-performing authorities in England.

Nearly one in three 11-year-olds failed benchmark mathematics and English exams in the county this year, new figures revealed.

The Department for Education data showed 70% of 6,905 Year Six pupils in Suffolk secured at least a Level 4 grade in reading, writing and mathematics when sitting national curriculum tests, known as SATs.

It was the joint-fourth-worst pass rate out of 152 local authorities in England. Only Reading and Bradford (both 69%), Luton (68%) and Poole (63%) performed worse.

Last year the county was the joint third-worst with a 68% ranking.

It means Suffolk jumped only one place in the national league tables, despite pledges from the county council to tackle poor attainment at Key Stage 2.

But with the national average stagnating at 75%, Suffolk is now 5% behind.

It comes the day after the 2013 Ofsted report found 33% of children in Suffolk do not attend a primary school rated “good” or “outstanding” – affecting 30,000 pupils.

Suffolk County Council (SCC) launched its flagship Raising the Bar scheme last year amid widespread concern over poor performance across the educational spectrum. It was designed to overhaul standards and improve results.

Mark Bee, SCC leader, last night insisted the council was not “failing” in its leadership of education while pledging his “full backing” behind the initiative.

“We recognise things need to change but I do not believe there has been a failure of leadership at the council,” he said.

“Last year we needed a radical new approach to drive up educational standards and I am fully behind the Raising the Bar scheme.

“We have confidence that once the measures are in place it will work and schools will see significant step changes.

“But we said it will not be an instant change and will need to be given time.”

Lisa Chambers, SCC cabinet member for education, skills and young people, said: “We are taking the first steps of a long journey. The first phase of the School Organisation Review is nearly complete and we have some really exciting programmes lined up to drive up standards. I have faith in Raising the Bar.”

Click here to see how each primary school in Suffolk performed in the latest tests.