The former Master of the National Maternity Hospital has claimed that the site for the new National Maternity Hospital is still under religious control.
Speaking on RTÉ's Marian Finunace show, Dr Peter Boylan said that the Sisters of Charity who own the site at St Vincent's Hospital have not yet received permission from the Vatican to change its status to a secular structure.
Dr Boylan said the project should be paused and not proceed any further until the board of St Vincent's Hospital and the Sisters of Charity produce "credible documentary evidence" that they have permission from the Vatican to relinquish ownership of the land.
He said that if the new National Maternity Hospital is completed and the issue has not been agreed it would prevent procedures such as IVF, abortions and vasectomies going ahead.
He said if the site is not removed from the Catholic ownership the project is "dead in the water".
In a statement, the Religious Sisters of Charity said they are "confident that the smooth legal transfer" of their shares in St Vincent's Healthcare Group is "imminent".
It said the Archbishop of Dublin has approved and recommended its decision to the Vatican for formal sign off and it is "confident of a positive outcome shortly".
The statement said this process "has not and should not" delay the new hospital project in any way.
The Diocese of Dublin has said the matter has been referred to the Holy See and "is likely to be examined by the charity regulator here if there is any change in the nature of the charity".
The National Maternity Hospital also issued a statement saying its new hospital will have complete clinical independence and will provide all healthcare services available under Irish law.