Figures suggest there has been a massive increase in British nationals becoming naturalised Irish citizens.
Fine Gael Senator Neale Richmond, who obtained the figures, says this is in the wake of the Brexit referendum.
He says British nationals living here, who do not qualify for a passport through lineage, are increasingly applying for citizenship.
In 2014, 51 UK citizens became naturalised Irish citizens.
This figure increased marginally to 54 naturalisations in 2015.
However that figure nearly doubled to 98 in 2016, the year of the Brexit vote, and spiked to 529 last year.
Senator Richmond says: "Already we've seen a massive increase in applications for passports by eligible citizens living in Northern Ireland and in Great Britain.
"Now, figures released to me by the Department of Justice have shown that increasingly British nationals living here, who don't qualify for a passport through lineage, are applying for Irish citizenship.
"Such a spike is clearly tied to the Brexit referendum and the uncertainty that has prevailed since the vote.
"There over 300,000 British nationals living in the state and it is estimated that about one-third of these would not qualify for an Irish passport through lineage.
"Many of these are now looking to become naturalised Irish citizens for a host of reasons.
"This is a good news story and these new Irish citizens should be commended for their decision and thanked for their positive contribution to our society", he adds.
People may be eligible to apply for Irish citizenship by naturalisation if they are living in the State or married to an Irish citizen - as well as a number of other conditions.
Naturalised citizens must also make a declaration of fidelity to the nation and loyalty to the State.