Government plans to eliminate the "three-for-two" seating arrangement on school buses means in excess of 5,500 students may no longer have seats on their school buses, school representatives have claimed.
Students who go to schools that are not within their catchment area, or who live close to their school, are not automatically entitled to places on buses.
Instead, Bus Éireann has up until now allocated these "concessionary" pupils a seat on a "three for two" basis, where one is available for them.
But according to the Irish Vocational Education Association (IVEA), the introduction of the new rules, while welcome, means more than 5,500 students are likely to lose out.
It says Vocational Educational Committees (VECs) may be forced to prioritise students in exam years when allocating any available places.
Parents who opt to send their children to schools outside their local catchment area may also have to move them to a local school or pay for a private bus operator to bring them to their current school, it believes.
In a letter sent last week to VECs, which co-ordinate the school transport scheme, Bus Éireann acknowledged that it would not be possible to accommodate the "vast majority" of students attending schools outside their local catchment areas.
This is because of the Department of Education's decision to reduce the capacity of school buses to a one to one ratio, the letter says.
A Bus Éireann spokeswoman yesterday said it estimated there were some 7,500 pupils attending schools outside their catchment area and a further 1,200 students who live less than three miles from school.
Michael Moriarty of the IVEA said the new rules meant many parents would now be faced with a dilemma.
"Parents might have to organise private transport, or revert back to a school in their catchment area," he said. "But if a student has to go to a school in their local catchment area, the school may not have the capacity to take them."
These schools may also not offer students the same subject choices as in their old school, and may require parents to pay for new books and/or school uniform, he said.
A spokeswoman for the Department of Education said a number of children were currently carried where space permitted, and on a three for two basis.
"These passengers may continue to avail of school transport if there are individual seats available on the bus," she said.