Frontline gardaí said “absolute clarity” on enforcing mandatory face masks on public transport should have been provided long before the provisions came into effect early on Monday.
The Garda Representative Association said the problem again illustrated the absence of police on the Covid-19 public health expert body.
GRA general secretary Pat Ennis said: "This issue has arisen – yet again – because of the absence of professional policing competence at the heart of decision-making in managing the Covid-19 crisis.
"The mandatory wearing of facemasks on public transport has been discussed for weeks. Had there been a policing presence on NPHET, which made the recommendation, this issue would surely have been flagged.”
He said his members found out through the media on Friday that criminal sanctions could be imposed for not wearing masks on public transport.
“And we were only told by email on Sunday at around 7.30pm that we were to enforce the regulations by referring infractions to the DPP for direction.”
He said that while gardaí board public transport every day to enforce the law what was expected of gardaí on the mask issue was “only gradually becoming clear”.
He said: "The dangers of discord and altercations between passengers on one hand and public transport workers and gardaí on the other are increased by this sloppy approach to public communication.
"Public transport is a working environment for our members, so absolute clarity should have been provided long in advance of Sunday evening."
Antoinette Cunningham, general secretary of the Association of Garda Sergeants and Inspectors, said: "The statutory instrument is crystal clear in the authority that is vested on bus drivers, train operators and people from the National Transport Authority.”
She said those staff must go through a number of steps, and that only at the end of the process can they call the gardaí.
The National Bus and Rail Union said it is not the role of bus or train drivers to enforce the rules.
The body for private bus and coach operators, the Coach Tourism and Transport Council, said their members had “no clarity” on their legal obligations.
It said: “Operating in such a legal lacunae has very real and obvious consequences going by the needless death of a bus driver who was involved in a serious confrontation with passengers over their failure to wear facemasks in France in the past few days.”