Secret messages between official German representatives in Dublin and Berlin during the early years of the second World War were concerned with preserving Ireland's neutrality, according to documents released in London yesterday.
Dominions Office files held at the Public Record Office reveal that the British government was so alarmed by the exchanges that it urged Dublin to seize the wireless used to send the messages to Germany.
According to the files, when the former Taoiseach, Eamon de Valera, rejected the offer of German military assistance in the event of an attack, Hitler ordered the head of the German legation in Dublin, Dr Eduard Hempel, to renew his promise of non-aggression against Ireland provided neutrality was guaranteed.
In London, the messages sent by Dr Hempel on his wireless were being monitored and the prime minister, Winston Churchill, described the situation as "abominable".
Commenting on the wireless messages, Churchill said: "It might be possible to take stronger action against southern Ireland and to force them to dismiss the enemy representative they have. Their conduct in the war will never be forgiven by the British nation unless it is amended before the end. This in itself would be a great disaster. It is our duty to save these people from themselves."
The Dominions Office also noted that even Dr Hempel had expressed reservations about sending the secret messages. He commented: "Nothing would bring disaster to Irish neutrality more swiftly or easier than another transmission."
Other documents released yesterday reveal that in 1920 senior British army officers were discussing a "recognised and controlled" policy of reprisals to stamp out the "treachery of local civilians" and "rebels" in Ireland.
"If British policy in Ireland is to be that of an eye for an eye, a tooth for a tooth, everyone should know it," the chief of the Imperial General Staff wrote in October 1920.
"The present system of uncontrolled reprisals, not approved yet condoned by the government, is to be condemned in every way.
"It must lead to great hardship even to loyal citizens and offers every opportunity to evil-disposed persons to commit crimes and satisfy their own private animosities."