Details of correspondence and government letters on the 1989 rugby tour controversy have been released by the National Archives as part of the 30-year rule.
The IRFU was widely criticised at the time after its committee allowed international board members to attend the sporting event despite government opposition.
The event was held in celebration of the centenary of the South African Rugby Board (SARB) in 1989.
At the time, apartheid South Africa was under a blanket boycott by many international sporting bodies.
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Among those taking part was Irish rugby veteran Willie John McBride, who managed the visitors’ side and had been under political pressure not to attend the tour.
The former Ireland captain was asked by the Sunday Independent about the opposition.
He was quoted as saying: “There is no reason why I shouldn’t go. I have the blessing of the Rugby Union.”
Referring to an attack on him by the anti-apartheid movement, he said: “I wouldn’t expect anything else. They are political. I believe in communication of people through sport and that is the way it should be.
“I believe in trying to break down barriers.”
After the tour, Mr McBride said rugby players should be allowed to play against “whomever they please without politics spoiling everything”.
However, in a press statement issued weeks after the tour, GP Moss, secretary of the IRFU, said it was concerned that its recognition of the event had “aroused reaction and controversy”.
“This occasion had been approved by the International Rugby Football Board and it was agreed by the committee of the IRFU that its international board members would attend,” the statement added.
It went on to say that, on reflection, it regretted its decision.
It said that no Irish team at any level or any other team from Ireland was allowed to play in South Africa, nor would teams from that country be invited to play in Ireland while the remainder of the apartheid laws in South Africa existed.
In a statement, Foreign Affairs Minister Gerard Collins said he was satisfied that the IRFU regretted its decision to take part in the centenary celebrations in South Africa.
He described it as “an unjustified decision which involved needless public controversy” in both Ireland and South Africa.
In a letter to Sean Farrell, first secretary at the embassy in London, Department of Foreign Affairs official Philomena Murnaghan revealed that the Irish government was outraged over the IRFU attendance.
She said the decision had been taken “in total disregard” for government policy on sporting contacts with South Africa.