Delegates were told that schools relying heavily on voluntary contributions will be forced to ask parents for more.

Budget 2009 abolished a range of grants to second-level schools, including grants for Transition Year, physics and chemistry, Leaving Cert Applied and Leaving Cert Vocational.

Out of 20 schools questioned by the union, 15 said they would be seeking an increase in parents' contributions to make up for the funding shortfall.

ASTI general secretary John White said the cuts were penetrating the "very soul" of schools.

"The research makes it clear that the entire school community will suffer because of the cutbacks — students, parents and teachers," he said.

The conference was also told more than half of second-level schools could be forced to reduce subject choice for senior cycle students from September.

Nine of the 20 schools surveyed said they would be curtailing, or dropping, programmes such as the Leaving Cert Applied and Transition Year.