Widespread weaknesses exist in the quality of provision for children with special educational needs in England, with many pupils put into the category because of poor teaching, a report has said.

Good quality provision coupled with effective identification of children with special educational needs is "not common", according to a review carried out by education watchdog Ofsted.

As many as half of all pupils identified for School Action, the lowest SEN category, would not be identified as having these needs if schools focused on improving teaching and learning for all with individual goals for improvement, the report said.

Teachers unions warned it was "unacceptable to scapegoat teachers" and spoke of the need for trained psychologists in schools.

Ofsted inspectors examined provision to the age of 19, carrying out 345 case studies and visiting 22 local authorities, 228 nurseries, schools and colleges.

Too often agencies focused simply on whether a service was being provided rather than whether it was effective, they said.

They added that parents' fears about inconsistencies in identifying special educational needs across the country were "well-founded".

Currently 1.7 million school-age children, or just over one in five pupils in England, are identified as having special educational needs.

The percentage identified as needing less intensive additional support, known as School Action and School Action Plus, has increased from 14 per cent in 2003 to 18.2 per cent in 2010.

Ofsted chief inspector Christine Gilbert said: "With over one in five children of school age in England identified as having special educational needs, it is vitally important that both the way they are identified, and the support they receive, work in the best interests of the children involved.

"Higher expectations of all children, and better teaching and learning, would lead to fewer children being identified as having special educational needs.

"For those children with complex and severe special needs, schools often need the help of health and social care services.

"All these services should be focused on the quality of what they are doing, and how well young people are doing as a result. At the moment too much effort is going into simply checking that extra services are being provided."