It is "high time for Mary Lou McDonald and Pearse Doherty to explain party accounts", according to a Government junior minister.
Fine Gael TD for Longford-Westmeath Peter Burke said Sinn Féin leader Ms McDonald and the party's national treasurer Mr Doherty "must offer clear explanations on the latest set of revelations concerning their party accounts and declarations".
Mr Burke's comments come as the Standard in Public Office (Sipo) commission launched an investigation into Sinn Féin's accounts following complaints.
As reported by The Irish Times, the complaints relate to "a series of discrepancies, contradictions and apparent mistakes in Sinn Féin’s financial statements and electoral spending returns".
The alleged discrepancies are said to amount to hundreds of thousands of euro in some cases.
'Highly unusual balances'
Describing the allegation against Sinn Féin as "extremely serious", Mr Burke said "Sinn Féin’s financial accounts and declarations are leaving serious questions that require immediate examination".
"There are obviously a series of highly unusual balances in Sinn Féin’s statutory accounts for a number of years which are overseen by Mary Lou McDonald and approved by national treasurer Pearse Doherty.
"As candidates for future taoiseach and minister for finance, it’s critical we have clear explanations without delay," he added.
The Sipo investigation comes after party's representatives were among the leading voices in criticism of Minister for Public Expenditure Paschal Donohoe after it emerged he failed to properly declare donations made to his election campaigns in 2016 and 2020.
Commenting last month on previously identified discrepancies in Sinn Féin's declarations to the watchdog, the party's housing spokesperson Eoin Ó Broin acknowledged the failure to declare over €2,000 worth of fees for the hiring of venues was "sloppy".
However, the Dublin Mid-West TD said there was a "world of difference" between controversy surrounding Mr Donohoe's election expenses and that of his party.