English pupils are among the most tested in the world and headteachers and staff are "overburdened" with Government initiatives, a report by a global watchdog has found.
The report by the Organisation for Economic Co-operation and Development (OECD) says the level of regulation imposed on schools risks backfiring and emphasises concerns about Ofsted inspections and league tables.
It warns that as more senior teaching staff reach retirement age, poor pay and conditions and unrealistic expectations from above could discourage others from taking their place.
The report, Improving School Leadership, looked at the quality of education in 19 of the 30 developed countries within its remit, including Belgium, Finland, England, Australia and Austria.
Researchers examined existing statistics combined with information from visits to English schools by a team of experts.
It found that while England provided examples of best practice in many areas including teacher training and sharing ideas, headteachers should be trusted more to run their own schools without Government interference.
"The sheer number of initiatives and programmes and the speed at which schools are expected to implement them may be counterproductive," it said.
"True improvement results from a balance of making best use of innovative ideas and concepts on the one hand and maintaining proven ones on the other."
The report singled out the Ofsted inspections for particular criticism and highlighted concerns that publishing inspection reports resulted in a "name and shame" culture.
"Preparing for one of the regular school inspections held by Ofsted means a lot of additional work and creates considerable strain for headteachers and staff alike," it said, adding that inspectors appeared to "turn the school upside down" during their time there.
The additional pressure created by publishing the results, it said, "is meant to stimulate the school's improvement efforts", while in reality there should be less emphasis on such external reports and more on "self-evalution".
It also described how results league tables were a bone of contention for headteachers and impacted negatively on poorer-performing schools.
"It is clear that the construction of the tables favours schools that are already advantaged," it said, adding that schools lower down the league tables had to fight against a "vicious circle" of low morale among staff and pupils, poor recruitment and retention of staff and always being the last choice of parents.
Beatriz Pont, the OECD report's author, said that while schools' accountability to parents, Government and the public at large was important, headteachers should be able to focus more on their pupils.
"At a time when governments are struggling to raise school performance, the men and women that run schools are frequently overburdened, underpaid and often nearing retirement, in many cases without a wide enough choice of qualified candidates to replace them," she said.
"In order to measure schools there is an increasing tendency to test and in the English study, we frequently heard complaints by headteachers and many on the ground that there has been too much testing.
"It would be more useful for headteachers to take their own evaluations in hand but they have to be given support in order to achieve that autonomy."
The OECD previously found that British school leavers entering the jobs market without qualifications face increasing hardships, with only 45 per cent of low-skilled youths finding employment within a year of leaving school.
John Dunford has been General Secretary of the Association of School and College Leaders, believes it would be better to chart the progress of the national education system by taking a sample of schools instead of testing each individual child.
“The testing system in this country is seriously overloaded,” he said. “Widespread testing means that teachers teach to the test and so the results are unreliable.
“You finish up with heads being overacountable, which tends to work against creativity and inventiveness, and children who are focusing too much time on exams and missing out on the broader aspects of education.”
English schoolchildren undergo a range of tests from the age of five to 18:
* Age five: Teachers assess children's all-round development against Early Years Foundation Stage profile
* Age seven: Key Stage One standard assessment tests assess pupils in the "Three Rs"
* Age 11: Key Stage Two sats tests pupils in English, Maths and Science.
* Age 14: Key Stage Three sats assesses pupils in core subjects for GCSEs.
* Age 16: GCSEs test pupils, typically in eight to 12 subjects.
* Age 17/18: AS and A Levels test pupils in three to six subjects. (By Aislinn Simpson Last Updated: 7:20PM BST 28 Aug 2008)