A PASSPORTS expert has said Irish people are not regarded with suspicion and that their good reputation may be to blame for the recent use of Irish documents in two high-profile espionage investigations.

Professor Michael Levi said the ease with which Irish citizens could transit within the European Union and to the United States made Irish documents very valuable.

However, he cautioned that two instances do not "make a trend" but that authorities elsewhere could now start to look less favourably on Irish passports.

Following the assassination of Mahmoud al-Mabhouh in Dubai on 20 January, it emerged that three of the suspects were travelling on false Irish passports.

The documents had genuine passport numbers, which belonged to real Irish people, and were described as high-quality forgeries.

Last week, another forged Irish passport was discovered after a long-running investigation by US authorities into a suspected Russian spy ring.

Professor Michael Levi of Cardiff University, an internationally renowned criminologist, said Irish passports, like those of other English-speaking countries, were particularly useful.

"Certainly, two incidents does not make a trend particularly but I think the point is that if you are an English-speaking person and you don't have an American passport, an Irish passport would be very useful," he said.

"Outside of travelling to the US, you've got a very large range of countries within the European Union that you can get to without a visa and any undue formalities.

"An Irish passport allows you to move across borders without any difficulty. Unless you have a dodgy passport as opposed to a genuine one or a very good forgery, you are not going to be stopped. If you are trying to get to and from the US, then of course the Irish facilities for clearing customs when you leave are another significant advantage."

Levi said that, perversely, it was a good reflection on Ireland's reputation that our passports would be used for nefarious reasons.

"In a way, it is a positive thing about the Irish reputation but one of the effects is that people might start looking more sceptically at these and [after Dubai] the United Kingdom. It is one of the reasons the British government got so annoyed about this. All this really shows is that an Irish passport is a handy thing to have if you're trying to travel within Europe and around the world more generally.

"There is no evidence that Irish passports are being disproportionately used and if they were, we should expect to be seeing them pop up a lot more in international crime."

Levi said the biggest risk with passports was still genuine passports that were issued to the wrong person through identity fraud.