The Minister for Health and Children, Mr Martin, did not know that an animal vaccine used to immunise sheep and cattle was given to Irish babies partaking in a drug trial until he read about it yesterday in the media.

"I am shocked that this could happen," the Minister told the Dail. "On a previous occasion, in relation to a similar related matter, I stated that children should never be used as guinea pigs in any trial, particularly without the consent of guardians or parents."

A full investigation would be carried out. The Eastern Regional Health Authority was making inquiries. It had confirmed its senior public health staff were not aware that the animal vaccine, Tribovax T, had been used in 1973 in place of the "3-in-1" Trivax for children manufactured by the Wellcome Foundation. The company, too, was asked to furnish information by the Irish Medicines Board, which would liaise with the UK Medicines Control Agency: "I will await the result of these inquiries before considering if further investigation is necessary."

Mr Denis Naughten (Fine Gael, Longford-Roscommon) asked whether Wellcome knew the vaccine was destined for animals rather than humans "in the light of the fact that the suspect lot of Tribovax T was administered as part of the drug trial now being investigated by the Laffoy commission and that reactions to all the vaccinations in this trial were returned to Wellcome".

It was not immediately clear whether the vaccine was administered as part of the State's vaccination programme in 1973 or whether it was used in a clinical trial that year - or a subsequent vaccine trial, the Minister replied: "We have referred any trial undertaken in an industrial school or orphanage to the Laffoy commission."

Mr John Gormley (Green, Dublin South East) said he would raise the issue at the next meeting of the Joint Oireachtas Committtee on Health and Children. The committee should have full powers to interview officials from the Department of Health, the ERHA and Wellcome. In reply to Ms Liz McManus (Labour, Wicklow) the Minister agreed it was a "serious issue" in terms of the integrity of the State's vaccination programme.