Sinn Féin has confirmed its voter database is being held on servers in Germany.
The Data Protection Commissioner has raised a number of concerns with the party over its Abú system.
Sinn Féin insists it is nothing more than information from the electoral register, which all parties have access to, despite suggestions to the contrary in media reports.
Party leader Mary Lou McDonald told The Pat Kenny Show: "This isn't something that's unique to us - every political party, every candidate who runs in election, canvasses the vote, has access to the electoral register and it's part and parcel of the process.
"The Abú system, as it's called in our case, is simply that: it is the returns - if you like - from canvasses.
"It's not pen and paper, it's now held on computers.
"It's stored in the European Union and it is all legally stored.
"I've seen this story in the media and there's been quite a heavy emphasis put on it, and that's fine."
Ms McDonald said the system was recently moved from the UK, on account of Brexit.
"It's stored in the European Union, it had been stored in London but obviously Brexit happened and that disrupted that.
"So it is legally held and stored with the EU, as per the law".
She then confirmed it is was stored in the German city of Frankfurt.
But she also claimed "a particular spin" was put on the story " I think to hype it up".
"This is canvas material, it's used for canvassing, it's used for electoral purposes - all of which is legal and part of the process and not unique to Sinn Féin".
She said the party is engaging with the Data Protection Commissioner.
Asked if the system contains information on likely Sinn Féin voters, she said: "Firstly, that would not be crossing the line: every political party, every political candidate users the electoral register to know who's registered to vote, and then to come and canvass your vote, and then to establish in their judgement the likelihood or otherwise of you voting for them.
"That is called special category information and data, it's specifically referenced in the law and it is entirely legal", she added.
