The Defence Forces are carrying out an investigation into claims that a number of its personnel were denied their constitutional right to vote in the local or European elections, because they didn't receive postal votes in time.
PDForra general secretary, Ger Guinan, whose association represents 6,500 enlisted personnel, said he wrote to military management a week in advance of voting to express concern that a number of his members still hadn't received postal votes.
For years Defence Forces personnel have voted in this manner and would normally expect to receive their postal vote at least a week in advance.
Mr Guinan said he received further complaints last Friday when polling stations had opened, that postal votes had still not arrived. He said he is "deeply concerned some people had lost their franchise to vote as a result."
A number of disgruntled soldiers and their families took to social media to highlight the issue.
Fianna Fáil spokesman for defence, Jack Chambers, said he is very concerned by what happened and will raise the issue in the Dáil: "It is extremely alarming that there are multiple reports of personnel in our Defence Forces who could not cast their vote in the recent elections.
"I have submitted a parliamentary question to Minister (for Defence) Kehoe to account and respond to this very serious development.
Many men and women who serve our State appear to have been denied their basic constitutional right to vote and this is completely unacceptable.
"Any restriction or delay in facilitating their right to vote denigrates and undermines the democratic process. The Defence Forces protect our democracy and if these reports are correct Minister Kehoe has delivered another blow to morale by not ensuring Defence Forces personnel could exercise their democratic rights," Mr Chambers added.
A Defence Forces spokesman said they are aware that some personnel claimed they did not receive a postal vote: "Inquiries are ongoing into these concerns, with a view to establishing the facts. This will include confirmation or otherwise that personnel were correctly registered."
He said the Defence Forces places a very high level of importance on ensuring that all personnel are provided with the opportunity to register for a postal vote(s), and receive said vote(s).