The Minister for Justice Michael McDowell described the Gardai's reponse to Saturday's riots in Dublin's city centre as "measured, proportionate and effective" but conceded the security threat had been underestimated.
"The blame for the turn of events last Saturday lies squarely with those who indulged in wanton violence and destruction on the streets of our capital city and with those who encouraged - either directly or indirectly - this sort of behaviour, " Mr McDowell told the Dail.
Mr McDowell said the Gardai had assessed the intelligence information available and concluded that any counter demonstration would not require a heavy security presence.
"However, and this was the really unexpected element, some 200-300 other people suddenly massed, many from streets and public houses close by, and began to attack garda officers with a range of missiles, including billiard balls, fireworks and smoke bombs. In the course of the rioting that followed two petrol bombs were hurled at the gardai," Mr McDowell said.
"I am satisfied that an enormous amount of preparation went in on the part of An Garda Síochána, and it is to be regretted that in the face of a reasonable low key law enforcement approach such vicious opposition was encountered.
"In the course of the planning all available policing methods were considered, including water cannon - its deployment was ruled out on the basis of the information available," he added.
He pointed out that on Saturday, 348 gardai were on duty in the city centre dedicated exclusively to the task of to policing the demonstration - a significantly higher number than would normally be deployed for a protest march on the scale envisaged through the city.
"This was an attack on civil society, on civil liberty and on the very nature of a republic. Those who engaged in the wanton and mindless violence last week-end carry no mandate and their actions cannot be justified" he concluded.