The Fine Gael leader, Mr Enda Kenny, has said today's arrests by gardaí investigating money laundering, raises grave questions for Sinn Féin.
Mr Kenny said the arrests and the reported involvement of a party member raised grave questions for Sinn Féin.
He called on the party to release an immediate statement in view of its "repeated denials" of involvement in criminal activity.
He also called on Sinn Féin to clarify whether anyone involved acted in an official capacity for the party in last June's elections.
He also called on it to clarify "its relationship with those involved."
Sinn Fein's Martin McGuinness said he would make no comment on the matter until he had more information.
Sinn Féin said it would wait for further information about the latest arrests before commenting. "Over the last four weeks we have seen people rush to judgment time and time again.
We would urge people to exercise caution on this occasion and allow the truth to come out," the party said in a statement.
Labour Party leader Pat Rabbitte said the Garda seizure of large amounts of money was an "astonishing development".
He said: "Whilst we await more details to emerge, it is of extreme concern that the Garda operation was specifically directed at IRA money laundering.
"However, even at this early stage, it appears that today's events are particularly significant in the context of the Northern bank robbery and subsequent denials by IRA and Sinn Fein."
The Green Party said there was even more cause for concern about the future of the Good Friday agreement and called on Sinn Fein to give a full and frank explanation.
Its leader Trevor Sargent said: "This highlights more than ever the liability which the IRA is to the peace process. It is not possible to maintain an illegal standing army without recourse to criminal fund-raising activity," he said.
