The St Vincent's Healthcare Group has rejected calls to sell the site of the new National Maternity Hospital.
In a statement, the group said that for the delivery of integrated patient care on the Elm Park Campus, it must retain ownership of the site.
It said the views of the hospital on this matter were understood and accepted by the Department of Health in 2017 and a lease option on the land accepted.
In recent days, the Government has said it will again engage with the group to buy the land for the new hospital.
In its first comment since the renewed controversy around the project, the group has insisted the new National Maternity Hospital will be clinically independent with no religious or Vatican influence.
The group said all medical procedures in accordance with the laws of the land are available in its hospitals, including terminations, tubal ligation and gender reassignment.
The group said it remains committed to the new National Maternity Hospital at Elm Park and the Mulvey Agreement as the best means of its delivery.
On the ownership issue, St Vincent's said the new National Maternity Hospital building will be owned by the State forever but the site will be owned by St Vincent's Healthcare group and leased to the state for 99 years plus 50.
It says that it must retain ownership of the land for "clinical, governance and operational reasons including the provision of a safe integrated system of care for patients between hospitals".
Minister for Health Stephen Donnelly outlined in recent days that he would like to have further engagement with all stakeholders in the National Maternity Hospital project, with a view to securing ownership of the site.
Labour leader Alan Kelly said the statement from the St Vincent's Healthcare Group has "upped the ante to the point where it makes the Government look ridiculous".
Speaking on RTÉ's Drivetime, he said it appears that a compulsory purchase order is the only way this can be sorted out, and "unfortunately that's going to take some time".
He said the statement made "a mockery" of the Taoiseach.
"Because the Taoiseach today, in a response to me and others, said essentially that Stephen Donnelly was going to be in negotiations and discussions," he said.
"There's no avoidance of doubt here, there will be no negotiation or discussions, they're saying that they will not sell the site."
There have been many issues in relation to women's healthcare and maternity care, Mr Kelly said, and they should not be "pumping €800 million plus into a building and a site that we don't own".
Speaking on the same programme, Minister of State Damien English said today's statement confirms what the Taoiseach and Tánaiste have said over the past few days, and "brings the clarity we need".