Relationship and marriage services risk losing state funding unless they adhere to a new government policy which says lesbian, gay, bisexual and transgender people should not be turned away.
The country's largest faith-based counselling group, Accord - which received £1.4 million from the Department of Child and Youth Affairs in 2016 - has long-excluded gay couples on religious grounds.
Accord - and 20 other agencies - have been told they cannot discriminate against people on grounds including sexuality if they want to continue receiving taxpayers' money.
Tusla, Ireland's government child and family agency, was quoted by The Times as saying: "Tusla recognises... the importance of public funded services operating services which are accessible to everyone."
Welcoming the shift in policy, Sinn Fein senator Fintan Warfield told the newspaper: "It is wrong for public monies to be channelled at organisations who fail to serve all sections of our society."
Premier has approached Accord, which is run by the Catholic Church in Ireland, for a comment.
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