Anglo-Irish relations would be gravely damaged if the death penalty was re-introduced in Britain and Irish people were executed for terrorist crimes, the Dublin government warned.
The Irish ambassador to the UK described the "grave anxiety" being felt in the Republic as Westminster prepared to debate capital punishment.
Conservative MP Sir Edward Gardner's motion on restoring the death penalty for murder was debated on July 13, 1983, with several amendments made to restrict capital punishment to certain categories of murder, including those "resulting from acts of terrorism", "by shooting or causing an explosion", and for security force deaths.
Five days before the debate, Ambassador Eamon Kennedy sent a letter on behalf of Irish Foreign Minister Peter Barry to Jim Prior (right), the Secretary of State for Northern Ireland.
Mr Kennedy said Mr Barry wanted the British to be clear on the implications for Anglo-Irish relations.
"The execution of Irish people under British law for politically inspired offences would almost certainly create a situation worse than anything our two governments have experienced during the past 13 years," he wrote. "The IRA, the INLA and other terrorist organisations would take full advantage of the opportunity."
Mr Kennedy stressed the fears were not exaggerated. "In suggesting that you might consider mentioning to your Government colleagues the grave anxiety we feel in Dublin, I should stress that the Irish government will respect the fact that the vote on this motion is a matter of conscience for the individual members of the House of Commons."
Sir Edward Gardner's motion was voted down.