The Cabinet had approved Ireland's support for EU regulations on stem-cell research, the Tánaiste, Ms Harney, told the Dáil.
"What we are doing is ensuring that in those member-states, where it is ethical and legal, it will be done under strict safeguards, guidelines and controls and not in the kind of unsatisfactory free-for-all situation which exists elsewhere. This is the issue."
She added that no new embryos could be created for the purpose of that research. "These embryos cannot be used if adult stem cells can be used and the applicants have to prove this to an ethical committee. The strongest possible guidelines are being put in place.
"Scientists will have to share the stem lines to avoid having to create unnecessary ones. That is a fact. The EU Commission has to come back in 2005 having reviewed the outcome in regard to the research."
She said the issue represented "a grey, complex area and sensitive. . ." Ms Harney said that as one of the countries which sought the guidelines it would be wrong for Ireland to use its vote to block them and to have an uncontrolled situation.
Mr John Bruton, a former Fine Gael taoiseach, asked if Ms Harney was aware that technology was now available allowing in vitro fertilisation to take place without the creation of spare embryos. He asked if she believed that the embryos in question were human.
"If they are human, do they have any human rights in the Tánaiste's opinion? If they have human rights, do the human rights of the embryos in question encompass the right not to be deliberately killed?" He asked if Ms Harney thought she might be accused of being a hypocrite by voting to allow Irish taxpayers' money to be used to pay for something in another country which was illegal in Ireland.
Ms Harney said she was not a scientist and would not pretend to be one. "While I am not familiar with all the developments in science, in recent weeks I have spoken to a number of scientists who differ on this matter, which is not black and white.
"Some scientists take the view Deputy Bruton has expressed that adult stem cells can do what is necessary and others take the view that the embryonic cells are much more versatile and can be converted into any one of the 210 cells we have in our bodies whereas adult cells can only be used for the purpose for which they were taken.
"Clearly those embryos have the potential to become a human being if implanted in a woman. We are talking here about supernumerary embryos that remain after IVF treatment and embryos that were created before June 2002, which is the cut-off date, although I accept that the European Parliament wanted that date to be removed."
Mr Gay Mitchell (FG, Dublin South Central) said that while the Tánaiste had consulted Ministers individually, the Dáil had not been involved beyond the examination by the sub-committee on European Scrutiny of the Joint Committee on European Affairs which had scrutinised the issue. "An emotional argument has been used. The commission on assisted reproduction had not produced a report. No Green Paper was produced. No concern was taken of the views expressed by the joint Oireachtas committee which adjudicated on the matter."