British military chiefs are facing a reprimand over the unapproved landing of an Royal Air Force aircraft at Shannon Airport.
The Hercules transport plane landed on 29 December without seeking clearance from the Government in advance.
Minister for Foreign Affairs Charlie Flanagan said: "The Government views breaches of the procedures set down for the granting of permission for such landings with the utmost seriousness.
"I have instructed my officials to discuss the matter further with the British Embassy with a view to ensuring that correct procedures are followed in future."
The British Embassy in Dublin told officials here that the RAF Hercules landed in Shannon to refuel.
Permission should have been sought in advance and assurances given that the aircraft was unarmed, carried no cargo of arms, ammunition or explosives and that it was not on an intelligence-gathering mission or a military exercise or operation.
British diplomats subsequently said there had been a "communication breakdown".
"The embassy has confirmed in writing that the purpose of the landing was refuelling, and that the flight was unarmed; carried no arms, ammunition or explosives; and was not engaged in intelligence-gathering nor formed part of a military exercise or operation," Mr Flanagan added.
Twenty-one other RAF flights followed the correct procedures to land in Ireland last year.
Independent TD Clare Daly revealed the information in a Dáil question and called for closer scrutiny of NATO planes.
"It is utterly shocking that a foreign military aircraft landed without permission from the Department of Foreign Affairs on Irish soil," she said.
"This is a total affront to our sovereignty and any notion of neutrality.
"The minister should be before the Dáil, apologising and assuring us of the measures he has put in place to prevent a recurrence," she said