An international row has erupted after Slovak authorities claimed Dublin knew about high grade explosives unwittingly smuggled into Ireland.

It was claimed yesterday that Slovak police informed the captain of a Dublin-bound flight and authorities here that the deadly RDX plastic explosive was on board.

As a major diplomatic incident loomed, the Slovaks claimed they had informed Dublin Airport that the materials were on a flight here three days before action was taken. Dublin Airport categorically denied such knowledge.

Several news outlets in Slovakia quoted sources from the country's Ministry of the Interior as saying that Irish officials were notified, while the flight was in the air, that a passenger would be arriving with highgrade explosives.

The Dublin Airport Authority (DAA) has flatly denied the reports, telling the Herald: “We didn't get any message or contact at all. The first we heard about this was yesterday when Airport Police Control was notified.”

A source in Slovakia said that a telex – a wire message – is believed to have been sent. However, a DAA spokesperson was emphatic that “no breach of security took place at Dublin Airport whatsoever”.

In a further twist today, Slovakian police alleged that the flight’s captain was informed while en route to Dublin.

The statement comes after gardai and Irish Army bomb disposal experts were forced to close down a section of the capital on Monday while they removed around 90 grams of RDX explosives from the baggage of Slovakian man Stefan Gonda.

The material was planted in the 49-year-old electrician's luggage on Saturday as part of a security tests at a Slovakian airport that were horribly wrong.

An Irish Defence Forces spokesperson said: “It wasn't a bomb or device. Other parts or components would have had to be put with it to make a bomb.”

However, security exports say that the material was equivalent in strength roughly to two grenades and could easily have blown up a building if combined with a detonator.

Gardai and the army launched a major security operation on Dorset Street, evacuating homes and businesses.

They then entered a flat and arrested Mr Gonda under the Offences Against the State Act.

It quickly emerged that he was entirely innocent and that Slovak authorities had planted the explosives in his luggage as he returned to Ireland after a Christmas break.

The Republic's Department of Justice 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.”

In all, “eight special items” had been placed in the baggage of passengers leaving Poprad-Tatry Airport.

The bizarre plan was for sniffer dogs to identify the suspect packages, but only seven were found. Police in Slovakia have been heavily criticised for the operation but say they used real travellers so that it would be a real environment.

The Slovakian Minister for the Interior, Robert Kalinak, has conveyed to Irish Justice Minister Dermot Ahern his government's “profound regret” for this incident.

However, Mr Ahern has appointed a Chief Superintendent “to investigate fully the circumstances surrounding the incident”.

The DAA today said it couldn't have acted any better under the circumstances. A spokeswoman said that they received “absolutely no contact” from Slovakia until yesterday morning.

“There is no security screening on arrival at any international airport. Passengers are deemed to be security checked at the point of departure, adding: “The fault lies at that airport.”

Fine Gael's Charles Flanagan said: “The fact that a foreign police force didn't see fit to contact their Irish counterparts about a high level sting operation is completely intolerable.”

He said that the Slovakian Ambassador should be called in by the Government “to offer a full account and explanation as to exactly how this debacle came about.”

Chris Yates, an aviation expert, said that “there are questions to be asked as to why the information wasn’t picked up in Dublin and action taken.

He pointed out that if the explosive had leaked, the Slovak man would face serious questions the next time he tried to pass through airport security with the same bag.