MORE than one in 10 HSC students at independent schools made an application for disability provisions last year, almost twice the rate of public school students, new figures show.

Eleven per cent of all HSC students at independent schools applied for the special assistance - which can include rest breaks, extra exam time, a scribe or a sign interpreter for students who have learning or medical difficulties - compared with 6.2 per cent of public school students.

The rate of applications at Catholic systemic schools was 8.6 per cent, according to figures published by the Board of Studies.

The disparity between the rate of applications from government and non-government schools is consistent with a trend that last year prompted an investigation by the NSW Ombudsman into the ''drivers and barriers'' for accessing the program.

A report commissioned by the Board of Studies in 2011 found no evidence of unwarranted claims but did find the application process could disadvantage some parents from making applications, including some from low socio-economic backgrounds.

More than half of the 5464 applications last year came from non-government schools - 18.4 per cent came from Catholic schools and 34.3 per cent from independent schools, compared with 47.3 per cent from public schools.

The most common provision for students was extra time to rest, which is approved for students with ''pain, anxiety or concentration issues who have difficulty completing the examination without a break'', which was approved for 2640 students.

According to figures collected by the Commonwealth government, three-quarters of disabled students in NSW attend public schools.

The provisions cover a wider range of difficulties than disabilities, such as feeding breaks for new mothers who may require time to breastfeed, which was approved for six students.

An external review of the Disability Provisions Program, commissioned by the Board of Studies in 2011, found costs and distance could be barriers to some students accessing the program.

''The inability of parents or schools to pay for specialist reports disadvantages students,'' wrote authors Damian Ellis and Beverley Johnson. ''Students who are at a considerable distance from medical centres find it difficult to gain access to professional reports.''

But a spokeswoman for the Board of Studies said they did not expect students to provide detailed or expensive reports.

''Students who are receiving ongoing care for an existing condition will have access to a diagnosis from their regular healthcare provider,'' she said.

Changes to the system since the 2011 review include providing information in non-English languages for parents and students and a test to help teachers diagnose students' reading problems.