The UN has called on Ireland to amend equality legislation so children can enrol in local schools regardless of their religion or lack of.
In its latest report on Ireland, the UN's Committee on the Rights of the Child (UNCRC) also called for effective and accessible alternatives to be provided for children who wish to opt out of religion classes in schools.
The UNCRC said it is concerned schools continue to practice discriminatory policies on the basis of a child's religion, and also on the basis of whether the child's parents were former students of a school.
In its strongest recommendations yet on the issue of schooling and the lack of diversity of provision here, the committee said Ireland should take concrete measures to significantly increase the availability of non and multi-denominational education here.
It said this should be done "expeditiously".
It has also called on Ireland to establish an effective complaints mechanism for students in schools, criticising what it called "an incomplete complaints handling structure" in the sector.
98% of primary schools here and many second-level schools are controlled by religious organisations, the vast majority by the Catholic Church.
The UN's recommendations have been welcomed by a variety of groups campaigning for the end of religious dominance in education.
Children's rights organisation EQUATE called on political parties to seriously reflect on the committee's findings and to commit to making equality in classrooms a reality.
A group representing parents campaigning for change, Education Equality, has said urgent action is needed from the incoming government to end religious discrimination in relation to access to schools.
It said the findings show that the current situation is unsustainable.
Advocacy group Atheist Ireland said it's particularly pleased that the committee has specifically called for changes to the Equal Status Act.
Overall, the UN report contains 81 recommendations for change.
They include recommendations to combat what the committee calls the discrimination and stigmatisation of Traveller and Roma children and their families.
The committee expressed "deep concern" about the number of Traveller children with no access to adequate water and sanitation, and about families affected by homelessness living in inappropriate temporary or emergency accommodation on a long-term basis.
It recommended the views of children should be heard in matters that concern them.
It calls for the views of the child to be heard in court and for the cost of an expert to support the child in such circumstances to be covered by the State.
The committee said abortion should be decriminalised in all circumstances.
It said sexual and reproductive health education should be made mandatory in schools.
The Department of Children and Youth Affairs has said the UN's observations will be referred to government departments and agencies for their attention.
Chief Commissioner of the Irish Human Rights and Equality Commission Emily Logan said Ireland has come a long way on “the protection and promotion of children's rights. However, a great deal of work remains to be done".
"These concluding observations form a clear 'to do' list for the State to bring its law, policy and practice in line with international standards on the human rights of children," Ms Logan added.