Serious concerns were raised at a Cabinet meeting about the lack of security measures at concert and sport venues in Ireland.
Super Junior Minister Finian McGrath is understood to have told colleagues he had "serious concerns for public safety" in the wake of the horrific concert bombing in Manchester.
Mr McGrath and Transport Minister Shane Ross both asked Justice Minister Frances Fitzgerald for assurances on the State's preparations for the eventuality of a terror attack.
But Mrs Fitzgerald insisted she had confidence in security arrangements currently used by gardaí to prevent a terrorism incident in Ireland.
Garda Commissioner Nóirín O'Sullivan briefed her yesterday morning on the response to the latest developments.
Gardaí are planning to take part in a series of exercises with specialist units from other European police forces in a bid to streamline the response to the growing threat from international terrorism.
The threat level in this country remains at "moderate" after the Manchester bombing. This means a terror attack here is possible, but not likely.
The Tánaiste said: "While there has been no change to the security assessment here and no specific information about a threat to us, the attack is a reminder that no one can be considered immune from those whose hatred of our values drives such evil acts."
This morning Ms O'Sullivan will again meet with the other commissioners and chiefs.
According to the Commissioner, the Garda force has to be conscious of the changing environment in which it operates.
She said the face of terrorism was changing and would continue to change and the force had to make sure it was able to respond to whatever threat arose.
Briefing documents given to ministers at yesterday's Cabinet meeting confirmed that there was a "small number of people here whose activities are a cause of concern in terms of supporting terrorism".
"They will continue to be monitored by authorities and, where evidence is available, they will face the full rigours of the law", a memo said.
Earlier, Defence Minister Paul Kehoe confirmed that security here will be kept under constant review.
"There is ongoing training between members of An Garda Síochána and the Defence Forces as to how deal with such challenges if something was to happen here in Ireland.
"This is kept under constant review. We have to look at what happened in Britain, of course.
"It would be very foolish if we didn't look at what happened in Britain and I know that Minister Frances Fitzgerald will be in touch with her counterpart in the UK, as will the Garda Commissioner with her counterpart in the UK, to look at how this happened," he said.
More than 400 gardaí will be drafted in to Slane Castle for this Saturday's sold-out Guns N' Roses concert.
A senior Garda source said that a "high-level" risk assessment is expected to be carried out prior to the event to ensure all precautions are put in place for the event, which will be attended by 83,000 fans.
"Nothing is being left to chance with this event. A major security operation will be put in place on the day and a full risk assessment is due to be carried out to highlight any potential weak points," he said.