The First Minister Mark Drakeford has said that people travelling into the country from England will be told to wear face masks by rail operators.
Face coverings continue to be required by law in all indoor public places in Cymru.
However, the UK government is ending the compulsory use of masks on trains in England next week.
Speaking on ITV's Good Morning Britain on Thursday, The First Minister said: "I think it will be difficult for people in England to know exactly what is required of them," adding that it would be "simpler and clearer for everybody" for the UK government to "bring itself in line" with Cymru and Scotland.
Transport for Wales said it supported the requirement to wear a face coverings while travelling by train.
Transport for Wales said "we will also continue to ask passengers to wear face coverings on Transport for Wales services which have part, or all, of their journey in England.
"The risk of catching Covid-19 on public transport remains low and we would like to thank customers for helping to keep themselves, fellow passengers and our staff safe by following this advice."