Sites in Blanchardstown and Belcamp in Dublin are not right for the new National Children's Hospital, according to the Master of the Rotunda hospital, Sam Coulter Smith.
Mr Coulter Smith was speaking amid reports that Connolly Hospital in Blanchardstown and a greenfield site in Belcamp near Coolock are among the frontrunners for the project.
Minister for Health James Reilly is to meet with the Taoiseach Enda Kenny and Tánaiste Eamon Gilmore in the coming days to discuss the plans, but Mr Kenny said the final decision will be taken collectively at Cabinet level.
The Rotunda Hospital is involved in a joint bid to have the project built at the Mater site in Dublin city centre, even though that idea was rejected by the planning board earlier this year.
However, Mr Coulter Smith believes it is still the right option, as the new children's hospital must be located with maternity and adult facilities.
He said: "As time has gone by, rumours are rife and no-one really understands what is happening as part of the process.
"My feeling would be that clinical needs are paramount, outcomes are the only thing that are important in this situation and what we want is a hospital that can be truly tri-located."