Up to 40,000 people who are resident in Ireland but using a UK licence will be driving illegally if there is a no-deal Brexit on 31 October, the Government has warned.
Minister of State for European Affairs Helen McEntee said around 30,000 drivers have already swapped their licences this year, but warned of major consequences for those who do not do so by the end of October.
Speaking at the National Driving Licence Service in Santry in Dublin, Ms McEntee also said there is still a huge gap between what Ireland needs and what the UK is proposing.
She said that while a significant number have already changed to an Irish licence, there could be thousands of illegal drivers on Irish roads if the UK crashes out of the EU.
"We would encourage people to change over. It's a process that takes no longer than five to 10 days. It's €55," she said.
"If the UK were to become a third country they will no longer be recognised under EU legislation."
Drivers who do not exchange their UK licence before 31 October will be forced to take driving lessons and re-sit their theory and driving tests to get an Irish licence.
Road Safety Authority CEO Moyagh Murdock said: "This will not affect people that are (in Ireland) as a tourist or as a visitor, you will still be able to travel on a UK licence.
"There are many people who are still driving on a licence they may have acquired from Northern Ireland or in the UK over the years.
"We want to advise them that after October 31, in the event of a no-deal, it will not be recognised as a valid EU driving licence.
"Just like other third countries, you will have to go through a very different process and you may find that inconvenient. It could pose problems in terms of insurance and other matters.
"We have about 250 people a day applying to change from UK and Northern Ireland licences in the event of a hard deal."
Ms Murdock said that there are plans in place to increase capacity and staff numbers to deal with the expected influx of applications over the coming weeks.
Some 32,000 UK licences have been exchanged this year compared to 6,000 in 2018.
Ms Murdock added that gardaí will enforce the matter "as they see fit".
She continued: "Some people are maybe, through human nature, leaving it to the last minute to come forward and we really urge those people don't get caught and don't be stuck without a licence.
"The bigger concern is the fact that if you're involved in a collision, that opens up a lot of questions with your specific insurance company and people need to ascertain from those insurance companies where they stand if they're driving post the 31st of October with a non-EU licence and yet they are resident in this country.
"I think the awareness campaign here is to get people to take responsibility.
"It is not down to the government to advise people how to drive legally after Brexit."
Additional reporting: PA