The Conservative Party has called for an investigation into the Downing Street chief of staff, Morgan McSweeney, claiming he sought to mislead a UK election watchdog.
Mr McSweeney, a native of Macroom, Co Cork, has served in his current role since October last year.
While in opposition, he led a think-tank known as Labour Together, which is credited with helping the party prepare for its ultimate general election success in July 2024.
However, in 2021, it was fined £14,250 (€16,323) by the UK's Electoral Commission over its handling of almost £740,000 in donations.
The Conservative Party has published correspondence which suggests that Mr McSweeney was advised to describe the failure to declare the donations as an "admin error".
It has been met with criticism by many senior Labour figures, with the Deputy Prime Minister David Lammy describing the controversy as "muck-racking".
Labour Together has also insisted that the issue has been dealt with.
"The Electoral Commission's investigation, with which Labour Together fully co-operated, was completed in 2021. The outcome was made public and widely covered by the media at the time", it said in a statement.
Pat McFadden, the Secretary of State for Work and Pensions, told BBC Radio this morning that the Conservative Party was trying to "attack somebody who is very effective".
He described Mr McSweeney as an "integral part of Labour's general election campaign".
The Conservative Party is also calling for an investigation into Prime Minister Keir Starmer, claiming he failed to declare support from the think-tank Labour Together.
Downing Street has insisted that everything was properly declared.
Conservative Party chair Kevin Hollinrake claimed that Mr Starmer received help from Labour Together, which included "secret polling to help writing his speeches and behind the scenes campaigning".
The party has written to the Parliamentary Standards Commissioner.
