The Irish government has demanded that Slovakia explain how an unsuspecting airline passenger was allowed to carry high-grade explosives on a flight to Dublin in an apparently botched security exercise.

Slovakian agents randomly planted powerful RDX explosives in the 49-year-old electrician’s bag but took three days to warn Irish authorities they were undetected.

Irish police traced the man to an apartment in Dorset St in Dublin city centre. He was arrested but has since been released from custody.

Security sources said the explosive was one of eight items of planted by the Slovakian authorities in the luggage of unsuspecting passengers at Bratislava airport at the weekend as part of a test exercise. Seven items were reportedly detetected, but the eighth, RDX explosive, went through in the bag of the innocent electrician.

The Slovakian government has apologised for the incident and a full investigation is underway.

A statement from the Republic’s Department of Justice said that Slovakian authorities had tipped off airport police to the presence of the explosives.

“Following contact earlier today from the Slovakian authorities with the Airport Police at Dublin Airport, members of the Garda Síochána have recovered a small quantity of explosive material from the luggage of a passenger who had flown into Dublin from that country on Saturday last,” the statement said.

“It has since been established that this material was concealed without his knowledge or consent in the passenger’s luggage as part of an airport security exercise by the authorities in Slovakia.

“The Slovakian Minister for the Interior has conveyed to Justice Minister Dermot Ahern his Government’s profound regret for this incident.”

The Republic’s main opposition party, Fine Gael, has demanded an investigation into how the explosives had not been detected

Fine Gael Senator, Paschal Donohoe, described the discovery as “bizarre and extremely worrying”. Senator Donohoe called for explanations from the government on the incident.

“This is the latest in a string of explosives discoveries in central Dublin which is extremely worrying in itself. The explosives find today is a particularly bizarre case with the explosive substance apparently brought into this country as part of a foreign test exercise.

“The government must now explain how it got into this country, what it was doing here and why the proper authorities were not alerted in advance, if this was an official test exercise. We also need to know what steps are being taken to ensure that this doesn’t happen again.

“I would like to acknowledge and commend the work of the Gardaí in ensuring the safety of the residents and workers in the area.”