Sinn Féin has confirmed its voter database Abú is stored in Frankfurt, Germany.
The party is in correspondence with the Data Protection Commissioner after concerns were flagged that certain data may be held on voters without their knowledge.
The party has insisted its database, Abú, is the electoral register, which is available in libraries in compliance with GDPR legislation and rejected accusations it is harvesting information from social media.
Party representatives have consistently refused to state over the last number of weeks where the database is stored other than that it was held in the EU, within the law. Ms McDonald revealed on Thursday morning that it is kept in Frankfurt, Germany.
A spokesperson for the party has since clarified a company called Linode is paid to host and secure the data, and that it has been stored in Germany since 2019 "in anticipation of Brexit".
When asked why it was stored in Germany and not Ireland, Ms McDonald told the Dáil it was a "technical question".
"People shouldn't imagine that this is sort of shipped off in a crate to another jurisdiction, the important thing is that it's electronically and technically held in storage, safely, and more importantly, that the information is for electoral purposes and that's entirely necessary and entirely within the law," she said.
Ms McDonald claims her party reps did not give the location out of respect for the process with the Data Protection Commissioner.
"This system that we have is really an old-fashioned canvassing system, but it's no longer now held with pen and paper. It's held electronically in a database, and therefore we have to be just like every other organisation, every other political party, we have to be careful as to observing privacy regulations and the use of the data, and it is purely political, it's for electoral purposes, and all of that is allowable under the law," she added.
She said a "spin was put on" the story, "I think to hype it up" and repeated: "This is canvass 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 was "not crossing the line" if it recorded the likelihood of someone voting for Sinn Féin.
"Every political party, every political candidate, uses the electoral register to know who votes, you know who is registered to vote, and then to come and canvass your vote and to establish in their judgement, the likelihood or otherwise of you voting for them, and that is called special category information and data, it's specifically referenced in the law."
She repeated: "There's nothing nefarious, there's nothing untoward here."
"There's nothing new in this but of course, the new element is that things are stored electronically and there is obviously a more advanced way of doing this."
The matter is not closed with the DPC, as "these things are rarely closed overnight, they've asked a number of questions, we've answered them very comprehensively, they may have more questions, and the process will run.
"I'm satisfied that we are absolutely compliant, I can assure you, there is nothing untoward happening with the information that we get when we're out and about on our canvassing.
"It's a necessary part of our work."
Graham Doyle, a deputy commissioner at the Data Protection Commission confirmed his office “received comprehensive answers to the number of queries” his office had put to Sinn Fein.
Mr Doyle added his office “appreciated the promptness” of the correspondence from the party.
The office will review the answers over the coming days but noted due to the length and detail of the response, he could not state definitively when the matter would be closed or if more correspondence was required.