Minister Bruton says the Dáil "will have to debate" any possible amendment to the Equal Status Act
The Education Minister Richard Bruton says a new admissions bill will not remove the clause that allows schools to discriminate on the basis of religion.
Mr Bruton says the law will not be changed as part of his new plans for overhauling school admissions.
The previous government's plans did not include amending the Equal Status Act, which allows discrimination on religious grounds.
Minister Bruton says he is planning his own new rules on school admissions, but there will have to be a Dáil debate before any decision is made.
"There is constitutional protection for religions within our constitution and the last Oireachtas committee recognised that there is a difficulty here. That has to be recognised," he said.
On Monday, Mr Bruton announced plans for 400 multi and non-denominational schools by 2030.
But the director of children's rights organisation Equate, Michael Barron, said: "Minister Bruton's plan is ambitious and with the proper roadmap is achievable."
"It must, however, be accompanied by reform of the Equal Status Act and the ending of the 'baptism barrier'."
Some 95% of Irish state schools are faith schools, and 90% of these are under the patronage of the Catholic church.
These schools can legally refuse to admit children from different faiths or none - while in six counties there are no multi or non-denominational school options at primary level.
Earlier this year, the UN Committee on the Rights of Children found that Ireland's international human rights obligations require the Government to take concrete actions to provide opt-outs for children during religion classes, to end the religious discrimination in schools admissions and to provide more multi-denominational schools.
Similar recommendations were also made by the Forum on Patronage and Pluralism in 2012.