The wearing of face masks or face coverings will be compulsory on public transport from Monday.
Face coverings became mandatory on public transport two weeks ago, but there has been no enforcement to date.
However, Taoiseach Micheál Martin has confirmed that the necessary regulations to enforce the rule are being signed tonight.
It means the National Transport Authority will have the authority to tell people that they can’t travel on bus or trains if not wearing a mask.
Gardaí can be called to enforce the new rules if necessary.
Speaking this afternoon, Micheál Martin said: "If people persist in disobeying, then gardaí can be called - but we don't envisage that to be necessary.
"My experience has always been from earlier times that when you say to people it's against the law, people will actually conform - basically people will not be allowed stay on buses without a mask, or trains for that matter."
Dermot O'Leary, general secretary of the NRBU, said there now seems to be confusion over who will police the rules.
He said: "We've made it very clear from the very start... that our frontline staffs will not be policing this.
"We're adamant that we don't want to put our members in a situation where they're going to be in conflict with members of the public who choose not to wear face coverings.
"Extra resources should be provided to the gardaí - they are the people who police our laws after all."
