Northern Ireland day visitors to the Republic face being fined and turned back by Gardai officers if they travel more than three miles (5km) over the border.
Irish police officers are set to be given emergency powers in order to enforce the measure by the Republic’s Health Minister, Stephen Donnelly.
Under the new rules, motorists from Northern Ireland can be ordered to leave the jurisdiction, the Sunday Times has reported.
The Republic’s lockdown, in place until March 5, restricts travel to just 5km - or 3.1 miles - unless it is essential.
Those found in breach face fines of €100, however, this currently does not apply to those travelling from Northern Ireland.
The new regulation is expected to specifically target non-residents from travelling more than three miles into the south, with high-visibility checkpoints being established on main routes from Northern Ireland into the Republic, such as the M1, N2 and M3.
Motorists travelling over the border without an essential reason can be ordered to turn back but also be fined by gardai, according to Irish Attorney General, Paul Gallagher.
It is part of a wider set of measures being implemented by the Irish cabinet with the aim of reducing the number of covid cases in the Republic.
These include mandatory quarantine at a designated facility for people who arrive in the Republic without a negative PCR test taken in the past 72 hours. Visa-free short term travel from South Africa and South America is suspended until at least March 5, the date the Republic’s level five restrictions are set to continue to.
The Sunday Times also reported that a resolution between Health Minister Robin Swann and his republic counterpart, Mr Donnelly over the sharing of passenger locator forms from travellers arriving in the Republic. Northern Ireland residents flying into the south will also have to provide home addresses on their forms, with the data passed on to authorities here.
Last week Irish Environment Minister Eamon Ryan appeared to confirm tougher penalties for cross-border motorists from Northern Ireland was on the cards.
“There is provision for someone coming down from the North, that they (gardai) can ask someone to turn back, and we’re looking to actually strengthen that (so) that we have the same fining capability in terms of traffic coming from whatever different direction,” he said.
The Republic’s Justice Minister Helen McEntee, however, has admitted such a cross-border regulation said it is “not straightforward” and “challenging” to crack down on people crossing the border unnecessarily, but something her government is actively exploring.
She said last Friday that any new laws had to be manageable for gardai to work with and stressed people had a moral obligation to avoid unnecessary travel. She said the vast majority of people were abiding by the rules.