The Garda Commissioner says it is not possible to close a loophole in the COVID-19 laws.
A gap in the legislation means 'day-trippers' from Northern Ireland do not have to abide by movement restrictions.
Drew Harris says his understanding is that the regulations are underpinned by the Health Act - which only applies to residents of the State - and can't extend beyond that.
Today, Commissioner Harris insisted there is close cooperation with the PSNI on the matter.
He observed: "The regulations can't extend further than the Health Act 1947... the regulations are a product of the act.
"This is all about whether you have a reasonable excuse to be out and about, what your essential travel is... the regulations apply to anyone in the State for other factors - large gatherings for instance.
"Those who are engaged in non-essential travel - in effect, 'day-tripping' - into this jurisdiction... they may have breached the law as it is in Northern Ireland.
"The [PSNI] are obviously responsible for that piece of enforcement, the same way as we would challenge those who are engaged in non-essential travel north into Northern Ireland as well."
He also stressed that the regulations doesn't go as far as the overall recommended restrictions from health officials - saying the regulations are instead "practically what we're able to enforce".
Commissioner Harris also said enforcement is 'not a big feature' of their policing of the coronavirus regulations.
The force says they've now invoked the regulations 76 times since they came into effect on April 6th.
Main image: Garda Commissioner Drew Harris. Photo: Sasko Lazarov/RollingNews.ie