The multinational company, which has since merged to become Glaxo Smith Kline, is at the centre of the controversy surrounding the inadvertent injection of some children in Dublin with the veterinary vaccine, Tribovax T rather than the 3-in-1 vaccine, Trivax in 1973.

The late 1960s and early 70s were a period of greatly increased numbers of adverse reactions in both Ireland and Britain.

In August 1973 the Eastern Health Board expressed its serious concern directly to Wellcome. The EHB drew specific attention to five lots of vaccine from which reactions were appearing most regularly.

The information was sent to the Head of Wellcome's Clinical Immunology Department, Dr AH Griffith who forwarded it to a senior colleague seeking precise details.

A couple of weeks later the results of tests carried out on the lots were relayed to Dr Griffith.

In a memo, thanking his colleague for the results, Dr Griffith said: "I am not sure whether they imply that these batches are abnormally reactogenic or whether, on intensive study, all batches are highly reactogenic.

"There seems to be no point in forwarding information to Dublin at this stage ... "

The Irish authorities are again investigating reports related to the bungled administration of child vaccines more than 30 years ago.

 The drug company involved has promised its full cooperation. It is becoming clear, however, that not only were Irish, and some British, children injected with highly toxic batches of whooping cough vaccine (Trivax), but also some Irish children were injected with an animal drug with a similar name (Tribovax T).

It seems that some health experts in the Republic Ireland and the United Kingdom were highly critical of the use of Trivax, but their concerns, and those of parents, were brushed aside. Among the experts was Gordon Stewart, emeritus professor of public health at Glasgow University, who advised the UK Department of Health in an unpublished 1989 report that he believed the vaccine to have been "too toxic."

The department is issuing the brand which contains mercury despite fears that it could be a cause of autism and other disorders. The decision flies in the face of European guidelines that warn it would be prudent to avoid such vaccines for children.

Mercury-free vaccines are available to the health department but last month all GPs and clinics, which inoculate more than 600,000 babies a year, were told all orders for the combined diphtheria, tetanus and pertussis (DTP) and Hib vaccine (which protects against a form of meningitis) would be met with a product containing thiomersal, which is almost 50% mercury. This was "in order to make good use of the current and future stocks available".

The previous policy was to supply a DTP Hib vaccine, Infanrix Hib, which does not contain mercury.

Two years ago medicine regulators in America and Europe recommended the mercury-containing preservative thiomersal should be phased out of vaccines "within the shortest possible time frame". This followed an announcement by the United States Food and Drug Administration (FDA) that accumulated mercury in vaccines given to babies under six months in America exceeded safety limits set by the Environmental Protection Agency.

In a related US study, researchers from the Centres for Disease Control and Prevention found a "statistically significant" association between thiomersal in vaccines and children with problems such as attention deficit disorder and speech and language learning delays.

Last year the European Agency for the Evaluation of Medicinal Products said: "For vaccination in infants and toddlers, as a precautionary measure it would be prudent to promote the general use of vaccines without thiomersal and other mercurial preservatives. Moreover, the use of the available thiomersal-free vaccines should be recommended for vaccination of newborns." The health department's decision will outrage parents already concerned that vaccines may damage their children. "It beggars belief," said Isabella Thomas, from Brighton, whose son Michael is autistic.

"To replace a vaccine which contains no mercury, which must be safer, with one which contains a toxic substance to use up stocks is disgraceful and irresponsible."