Teaching assistants do not improve attainment

The research, conducted by the Institute of Education on behalf of the Department for Children, Schools and Families (DCSF), found that pupils who were supported by a teaching assistant made less progress in school than their peers who received no support.

The more assistance pupils received, the less well they progressed academically.

Professor Blatchford, who led the research, blamed a lack of proper teacher training for the problem. He said less than a quarter of teacher know how to work effectively with teaching assistants.

He said: "The reasons why pupils have this support in the first place - lower achievement, learning and behaviour difficulties, social class - have all been accounted for in the analysis, so we cannot say that pupil characteristics are the cause of their slower progress."

Despite this, Blatchford's team found that teaching assistants reduce teachers' stress levels and improve classroom discipline.

Christina McAnea, head of education at Unison, described the report as "a wake up call".

She said: "Schools, local authorities and the government need to make sure they are deploying staff effectively. It's obvious that children with complex needs will require the most support from qualified teachers, yet too often they experience the reverse of this."

A spokesman for the DCSF said: "It's counter-intuitive to say that support staff do not affect pupil progress - there is clear evidence that there is a positive impact on where teaching assistants are trained and effectively deployed to deliver specific support programmes, alongside well-planned lessons."