A NSW Catholic school has been ordered to accept the daughter of a same-sex couple after the local diocese intervened.

The acting bishop for the Wilcannia-Forbes diocese, Kevin Manning, today said he was appalled by a decision taken by the Sacred Heart Primary School at Broken Hill to refuse a girl a kindergarten place on the basis of her parents' relationship.

The school has now offered the girl a place following his intervention, Bishop Manning told ABC local radio.

"I was absolutely appalled when I heard about it," Bishop Manning said.

"It's certainly something I wouldn't condone in any way."