Garda Commissioner Fachtna Murphy has said gardaí are investigating the possible fraudulent use of six Irish passports.
In particular, it is believed the passport details of a volunteer with Irish charity 'To Russia With Love' were used in a false passport held by a member of a Russian spy ring that was uncovered by officials in the US earlier this year.
The ten arrested in the US were later deported as part of an agreed swap with Russia.
The six Irish passport holders had been granted visas at the Russian Embassy in Dublin.
Commissioner Murphy said the gardaí have been working very closely with their US counterparts.
He added that the investigation has been ongoing for some time.
Commissioner Murphy said he is happy the changes brought about to Irish passports in 2005 have made a big difference to security of passports and most of the passports being investigated pre-date that time.
'To Russia with Love' Managing Director Debbie Deegan said gardaí informed a female volunteer last week that details from her passport had been used.
It is not known how the passport was accessed.
The Russian Embassy in Dublin said it has had no contact from the Government or from gardaí in relation to an investigation into the possible fraudulent use of Irish passport details.
This morning, an attaché at the embassy said he could not comment on what was a very sensitive matter except to say that the Russian government had great respect for the charity, which works with orphans, and its work.
A Department of Foreign Affairs spokeswoman said investigations by the gardaí and the Passport Office were ongoing.
She said the department could not comment on individual cases.
The garda investigation is separate from that set up to investigate the forgery of Irish passports by Israeli agents.
That investigation established that eight forged Irish passports were used by those believed to have been involved with the killing of a senior Hamas figure in Dubai and that an Israeli Government agency was responsible for the misuse and, most likely, the manufacture of the forged Irish passports.
