GARDAI may carry out random checks of US planes travelling through Shannon following the illegal transfer of a prisoner. The handcuffed and manacled US marine was discovered on board a US civilian aircraft at Shannon Airport last Sunday. Foreign Affairs Minister Dermot Ahern said the US authorities had failed to notify or seek the consent of the Government for the prisoner transfer, as required under international law. Mr Ahern, who was not notified about the incident until 5pm on Monday, immediately summoned the US Ambassador James Kenny to the Department of Foreign Affairs in Dublin. "He was pretty shocked. I think he saw the seriousness of what was at issue," said Mr Ahern, who has demanded a full report from the ambassador. A garda investigation into the incident, which has led to the biggest diplomatic clash between the Irish and US governments for over a decade, is also under way. Mr Ahern said he still accepted the US government's assurances that Shannon Airport was not being used for extraordinary rendition of prisoners. The Omni airways charter plane was en route from Kuwait to Shannon with the prisoner and 180 US troops on board and stopped in Shannon for servicing last Sunday afternoon. The US Embassy originally told the Department of Foreign Affairs it was a cleaner on board the aircraft who reported the presence of the prisoner. Ground handling firm, Servisair, said a flight crew member, not one of their contract cleaning staff, raised the alarm. "The flight crew informed Servisair in accordance with protocol and Servisair informed the airport duty manager, who took the matter further," said a spokesman. The duty manager boarded the aircraft at the request of the US Embassy and confirmed the presence of the handcuffed prisoner.