Disadvantaged schools tend to have a higher concentration of students with special needs because other schools turn them away, new research has found.

A study of 12 primary and post-primary schools by the Economic and Social Research Institute (ESRI) and the National Council for Special Education (NCSE) also found that some teachers feel underequipped to teach special classes because they lack training and experience.

Nearly 150 new special classes were started by schools during the past academic year alone, in addition to the 659 in existence. But some schools continue to use soft barriers in admissions policies to deter applications by parents of children who require extra supports.

The Education (Admission to Schools) Bill is expected to end such practices when it eventually comes into force, but experts say these soft barriers are deployed regularly.

"There's means and ways where they can write their admissions policy around those lines, and the parent then naturally feels their child won't be welcome," said Jennifer Doran, head of research with the NCSE. "Some schools, we understand, will suggest that they're not going to get the special educational resources, but they will, and we're very clear to say that to parents. Every school is resourced in the same way when it comes to special educational needs."

The Special Classes in Irish Schools study states that students in classes specifically designated for autistic spectrum disorders reported the most positive experiences, with special classes for students with no identified need showing negative outcomes.

This is because children who had lesson plans tailored to their needs experienced greater integration with mainstream classes and benefited from strong parental involvement, whereas students with no identified need tended to feel stigmatised in the classroom environment.

The report calls for a renewed effort to provide special educational needs (SEN) training to teachers, especially for those assigned to special needs classes. Additional professional support and SEN-specific qualifications greatly improve teaching capacity, it says. Furthermore, principals should also seek to implement a school-wide approach to inclusion, especially as many of the one in four students with a special educational need are in mainstream classes.

"The research identifies key opportunities to equip every young person with the skills they need to succeed at school," said report co-author Selina McCoy, from the ESRI. "Given the recent increase in the number of special classes in Ireland, it is an opportune time to apply this new evidence to ensure that special classes act as a valuable and effective resource for young people in Ireland."

In response to the study’s findings, the NCSE will release a set of guidelines on Tuesday for schools seeking to set up special classes.

The guidelines highlight the need for schools to encourage continuous professional development for their teachers to equip them with up-to-date SEN skills. They list examples of good practice for schools to foster “supportive and inclusive learning environments” for special needs students.

“Our research highlighted a number of worrying issues regarding special classes, such as students feeling negative about attending special classes and teachers feeling unprepared to teach in these settings,” said Ms Doran.“That is why we developed these guidelines – to provide good-practice points to schools to ensure that all students feel valued and welcomed under a whole-school approach to inclusion.”

Schools are able to apply for education grants to set up special classes across 12 categories of disability, including visual or hearing impairment, physical disability and autism.