The Ombudsman for Children Niall Mulldoon has said the use of reduced timetables in schools is a" serious" concern that is impacting on the rights of children.
He told the Oireachtas Committee on Education and Skills that he is concerned about the use of reduced timetables as informal suspensions - in response to challenging behaviour by a child that a school is finding difficult to manage.
Dr Mulldoon said that excluding a child's access to education is as an extremely "serious sanction" and that there are specific safeguards under Irish policy and legislation regarding its use.
He said the use of reduced timetables was "invisible", with no guidelines and no guidance on recording its use.
He added that reduced timetables could be a positive intervention in exceptional circumstances but he said safeguards were needed.
Dr Muldoon said evidence would suggest children with disabilities, children with emotional and behavioural difficulties or children from a different cultural background such as those in the Traveller or Roma communities are more adversely affected.
He said the impact of prolonged reduced timetables as an exclusionary measure on children should not be underestimated and can make them feel unwanted by the school community.
Groups representing pupils with special needs, intellectual disabilities and Traveller students are also appearing before the committee today to raise their concerns over reduced timetables.
Director of the Irish Traveller Movement, Bernard Joyce, told the Committee that he is concerned about the use of reduced timetables in managing challenging behaviour by children in the Traveller community.
He said the practice of reduced timetables for Travellers in particular stems from low expectations of Travellers.
Mr Joyce said there is the potential for legal action arising from the misuse of the practice for Travellers under the Equal Status Act.
He said legislation to control and monitor the use of reduced timetables must be put in place.
In its submission the Oireachtas committee, the Department of Education said that the responsibility for school attendance rests with the child and family agency, TUSLA.
It said the guidelines for schools published by TUSLA outline that any exclusion of a student for part of the school day can be deemed to be a suspension.
It said that all pupils who are enrolled in a school should attend for the full day except in exceptional circumstances.
It said reduced timetables should not be used as a behavioural management technique, or as a 'de facto' suspension or expulsion.
Adam Harris, of autism support group AsIAm, said reduced timetables had a "devastating" consequences for many "vulnerable" students.
He said that many students with autism were on reduced timetables despite concerns raised by their parents.
Mr Harris said in some cases parents who did not wish to have a reduced timetable were threatened with a suspension or expulsion process for not complying.
He said that in many instances reduced timetables were a symptom of a lack of resources and knowledge.