Security was being tested at two airports in Slovakia
Dublin Airport authorities were told a man was due to arrive carrying explosives planted by Slovakian police, officials in Slovakia have claimed.
Stefan Gonda, 49, unwittingly brought plastic explosives placed on him to test security at Poprad-Tatry Airport.
Irish police arrested him on Tuesday, three days after his flight. He was later released without charge.
Dublin Airport has rejected claims it was told. It is believed a telex was sent to a baggage handling firm.
Slovak chief of border police Tibor Mako claimed a test sample of explosives had been attached to the straps of the man's backpack.
He said it was detected by a sniffer dog but a policeman forgot to remove the sample then failed to tell his supervisor that the explosives were on board the plane.
Ivana Herkelova, director of Poprad-Tatry airport in north-east Slovakia, said the plane was on the runway when the error emerged but the pilot decided it was safe to fly.
"I think that the Foreign Police units made a mistake here and the aircraft should have been prohibited from taking off," she told Slovak newspaper SME.
In a statement, the Dublin Airport Authority said it had no contact from the authorities in Slovakia until Tuesday.
Reports suggest the warning message was faxed from Slovakia to luggage handling agent Servisair.
When Irish police were informed on Tuesday morning, the man's flat near Dublin city centre was cordoned off while bomb experts examined the scene.
Mr Gonda, a Slovakian electrician living in Dublin, was returning from his Christmas holidays.
His wife, Monika Gondova, told Slovak newspaper Pravda that he would not file a complaint against the police.
The explosives were among eight contraband items placed with passengers at Bratislava and Poprad-Tatry airports last weekend.
A spokesman for Irish Justice Minister Dermot Ahern said it "beggared belief" that the man had been allowed to board the flight, the Irish Independent reported.
He said the security operation was a "bit of a fiasco", but added that the minister had accepted an apology from Slovakia's deputy prime minister and interior minister Robert Kalinak.
Opposition politicians have called for Mr Kalinak to resign.
Slovak authorities were reportedly trying to test screening procedures for checked-in luggage by placing items with unwitting passengers.
The Irish Army said passengers had not been put in danger because the explosives were stable and not connected to any essential bomb parts such as a detonator or power supply.
Airport security has been stepped up in many countries following an alleged plot to bomb an airliner over the US city of Detroit on 25 December, though it was not clear if the Slovak test was linked to such efforts.