Some 25-30 people are thought to have travelled from Ireland to conflict zones since the Arab Spring, according to Minister for Justice Frances Fitzgerald.
She told the Dáil that while some travelled for humanitarian or family reasons, some are known to have participated in conflict and at least three had died in the fighting.
Ms Fitzgerald said a number had returned from the conflict zones and there was a small number of people based here who support extremism and would try to facilitate it.
She said these people were closely monitored by gardaí and there was close co-operation with intelligence services in other jurisdictions.
However, she said there was no specific information to suggest a threat to Ireland or that Ireland was being used as a transit hub.
The minister was responding to a question from Fianna Fáil TD Niall Collins, who said authorities in the United States had passed on information to gardaí.
He asked if she had examined the legality of removing passports or citizenship from people who engage in acts of terrorism aboard to which the Minister said she did have the power to remove citizenship.
Ms Fitzgerald told the Dáil the majority of people travelling to Syria do so through Turkey and it would be complex to prevent people travelling, but she would not rule out if she had evidence from the gardaí.
Mr Collins told the Minister that it was reported recently that a person who frequently features in international terrorist bulletins and is heavily involved in financing the so-called Islamic State has been living in south Dublin for 15 years.
He asked Minister Fitzgerald if the Criminal Assets Bureau could be used to investigate this issue.
The minister said legislation does allow this and it would be used if there is evidence to justify it.
She said she could not comment on a specific case, but if there was evidence in relation to anyone here supporting terrorism through their financial activity, that would be dealt with.
She said new legislation passing through the Senate would give further powers in this area.
