Foreign Affairs Minister Micheál Martin has denied that the Irish passport is a soft touch.
Minister Martin has been responding to Opposition questions about Irish passports being caught up in high profile international investigations.
Most recently, it was alleged that one of those arrested in the US on suspicion of being part of a Russian spy ring travelled on Irish documents.
Minister Martin said gardaí and passport office staff are now investigating the matter.
"What we are confronted with is an allegation in a US court that an individual travelled from Rome to Moscow on a false Irish passport," Minister Martin said.
"Our own investigating officers are working to establish the veracity of this allegation and to establish the nature of the evidence to substantiate this.
"Accordingly, it is premature to reach any conclusions or make any representations to other governments at this time."