But chief inspector says it is not all bad news as school effectiveness framework is launched
Poorly performing local authorities are to blame for slipping standards in some schools, it was agreed this week.
Education experts and teaching unions said they should be held responsible as it was revealed that the number of schools in special measures or causing concern in 2006-7 had doubled to 16.
The first annual report of Dr Bill Maxwell, the new chief inspector of education and training in Wales, highlighted below-par and wide variations in performances of local authorities.
The spotlight was on schools, with one in 10 reported as not doing as well as it should.
But unions defended them this week, saying the schools had maintained overall good teaching standards under difficult circumstances.
The launch of Dr Maxwell's report was held at St Joseph's RC Primary School in Newport.
Analysts later said the overall inspection results of LAs in the report were much more damning than those for schools.
One-third of their services were described as "poor" and two-thirds were deemed unlikely to improve, the worst result for five years. LAs - nine were inspected in 2006-7 - were also said not to be successful in working with "failing" schools to improve the performance of pupils.
The widening gap between Wales's best- and worst-performing schools has been well highlighted by TES Cymru. We broke details of the growing gulfs last month after obtaining a draft document of the School Effectiveness Framework, a strategy aimed at raising the performance of coasting schools and being implemented next month.
The framework was officially launched this week, alongside Dr Maxwell's report. Officials hope to make it a success, with greater collaboration between the Assembly government, local authorities and schools.
But academics behind the ambitious strategy are starting to doubt the ability of LAs to reverse the fortunes of some schools.
David Reynolds, professor of education at Plymouth University, said: "This pretty depressing report shows that educational performance has reached a plateau in Wales, with widening gaps in the performances of the best and worst schools.
"Worse still is the performance of LAs and their ability to do anything."
Professor David Egan, from the Cardiff School of Education at UWIC, said some LAs needed to refocus their priorities.
"The evidence is that effective authorities are those that think strategically and focus their work on improving standards within schools. Clearly they are stretched, but this is one of the most important areas and has a large impact on pupil performance."
Within the new framework, local authorities will have a leading role in ensuring appropriate support and resources to schools.
During his launch address, Dr Maxwell said: "We need to get to a position where local authorities routinely identify schools needing help first. We want them to get there before us."
Earlier he said: "In the past two years, a third of schools inspected had no outstanding features - what we might call coasting in many respects."
However, he said the system was not failing and there had been many positives. Overall quality of teaching was better than six years ago he said, and more schools were obtaining top inspection grades.
Geraint Davies, spokesman for the NASUWT Cymru, said: "There is only so much teachers can do, and to go that extra mile the schools need more support from their local authority."
But Gareth Jones, secretary of the Association of School and College Leaders Cymru, said: "Estyn policy has raised the bar on inspection making it harder for schools and teachers to achieve higher grades."
A spokesperson for the Welsh Local Government Association said: "The chief inspector's report shows approaches are paying off, with an increasing number of schools showing excellence.
"We must not be complacent, and we acknowledge the need to narrow the gap between the best and worst-performing schools."
Headteachers believe education services are in decline, page 5.
Leader, page 32.