The US military illegally flew a military prisoner into Shannon Airport aboard a civilian plane, it has emerged.
The prisoner, who was handcuffed and manacled, was a US marine convicted of a minor offence, Minister for Foreign Affairs Dermot Ahern said. He was found aboard the plane by a cleaner on Sunday afternoon.
While prisoners can legally be transported through Irish airports under Irish and international law, authorities are obliged to seek permission from the Department of Justice. This did not happen.
'This failure, though inadvertent, is unacceptable', says the Minister for Foreign Affairs, Dermot Ahern.
"This failure, though inadvertent, is unacceptable. It is a matter of gravest concern to the Irish Government," Mr Ahern said.
He stressed, however, that the incident was unconnected to claims that Shannon has been used illegally by the CIA to transport terrorism suspects under its extraordinary rendition programme.
Mr Ahern said the Cabinet discussed the incident this morning and it was decided the public should be informed immediately.
He said he was informed of the incident last night, 24 hours after it took place by the US embassy. He immediately summoned the US Ambassador who told him it was caused by an administrative error.
Ireland will carry out an investigation, Mr Ahern said, and the Ambassador undertook to carry out a review. The Minister also requested a written report from the US embassy.
There were approximately 180 marines aboard the flight when it landed.
A cleaner aboard the flight discovered the prisoner and immediately informed the Servisair duty officer at Shannon Airport who boarded the plane.
The officer saw the prisoner in the custody of US military police and, according to Mr Ahern, said the prisoner spoke with an American accent.
He then contacted the US embassy who informed the Government. The gardaí were also notified but did not board the Omni Air flight - an airline that regularly transports the US military.
A Garda spokesman said an investigation was underway.
Mr Ahern rejected any suggestion that the transportation of the prisoner had any connection to claims that Shannon has been used for the CIA's "extraordinary rendition" programme.
Minister for Foreign Affairs, Dermot Ahern
A Council of Europe report last week accused Ireland of being complicit in the rendition of terror suspects who are transported to suspected secret camps where they are allegedly interrogated and sometimes tortured.
The report by Swiss senator Dick Marty found prisoners had not been transported through Shannon but the airport had been used by CIA planes - disguised as civilian aircraft - for refuelling stops while on rendition operations.
"It has been the consistent position of the Irish Government that no aircraft can use Shannon for extraordinary rendition.
"While I would reiterate that this incident is unconnected to allegations of extraordinary rendition, it is essential - not least in terms of public confidence - that the Government take appropriate steps in response to such a breach," Mr Ahern said.