Minister for Transport Shane Ross says if his compulsory face coverings proposal is successful, it will likely be introduced in "the next few weeks."
The proposals are set to be discussed at a cabinet meeting today.
Speaking on RTE's Morning Ireland, Minister Ross said: "Social distancing rules on public transport has meant they're down to very very low levels, you're talking about 12 people on a double decker bus.
"We are going to get to a situation in the next few weeks where it's close to bursting and where there's not enough capacity on public transport.
"We've increased the capacity to 50% which will mean a lot more people can get on the buses and the trains but to match that, to protect people's health, we've made mandatory face masks so everybody getting on to public transport in the next few weeks or days, they'll have to wear a face mask."
Minister Ross did not give an exact date for when this could be introduced but said he expected it to be implemented "as soon as possible, in the next few weeks anyway."
Asked about the cost of face masks, the Minister said: "I suspect they (face coverings) will either be very cheap or they (people) will be able to make them themselves."
And he stressed that the masks would not need to be medical grade however, people would need to follow proper procedures when using them.
"The regulations will be made by the Department of Health but my understanding is that technically face masks mean medical masks for medical use, those won't be necessary.
"My understanding is that the requirements will probably go up on the website (HSE's site), but it won't be as stringent as people wearing very strong medical masks."
He added: "There's going to be a serious communications campaign accompanying this to make sure people know how to use them and feel familiar with them."
Some people will be exempt from wearing masks, including children aged under 13 and those with certain health issues.
"There's absolutely no intention to force people to wear face masks where it might be damaging to their health, there will be exceptions made", Minister Ross reiterated.
