Sinn Fein President Gerry Adams has held his first meeting with the Irish premier since police blamed the IRA for a £26.5m bank robbery in Belfast.
More than £26m was stolen from the Northern Bank
Mr Adams asked Bertie Ahern to explain his comments that the Sinn Fein leadership must have had prior knowledge of the raid.
The IRA has denied involvement in the 20 December raid on the Northern Bank.
Speaking after the meeting, Mr Adams welcomed comments from Mr Ahern that he was opposed to sanctioning his party.
"We put it to the taoiseach that profound difficulties have been compounded by the accusation which he made, and we asked him to stand up that accusation and he could not stand up that accusation," he said.
"I also want to welcome other remarks that the taoiseach made where he said the government was opposed to sanctions, the government was opposed to exclusion, to demonising or criminalising or to in anyway excluding any section of people."
However, Mr Adams acknowledged that the process was "in profound difficulties".
Mr Adams is concerned about sanctions
The Irish Government said it had told Sinn Fein to go away and consider its position.
Justice Minister Michael McDowell and Foreign Affairs Minister Dermot Ahern said they stood by the taoiseach's view that the IRA was behind the robbery.
The Irish Government confirmed its opposition to sanctions although the Mr Ahern said they were a matter for the British Government.
Mr McDowell said: "It was made very clear to them (Sinn Fein) that this was not a meeting at which the government was going to explain itself or the government was going to share intelligence with them or the government was going to set out the basis on which it had come to its conclusions."
He added: "There is no mandate for Sinn Fein to pursue a political path with violence."
Mr Ahern added: "There may well be consequences for them in the next Independent Monitoring Commission report."
The SDLP and the Ulster Unionists are also holding talks with the taoiseach on Tuesday.
The talks follow an assessment by the PSNI Chief Constable Hugh Orde that the IRA was behind the raid on the bank head office.
The BBC understands that the police have a list of suspected IRA figures whom they believe were involved, names which have been included in security briefings given to government.
On Monday, SDLP leader Mark Durkan said he did not believe Mr Adams' denial about the Northern Bank raid.
Prime Minister Tony Blair is to hold talks with Mr Adams at Chequers on Thursday when Mr Blair is expected to reiterate demands for the IRA to cease all paramilitary and criminal activity.
Mr Blair is also due to hold talks next week with Mr Ahern and the SDLP.
Two days later, the prime minister will meet Ulster Unionist leader David Trimble.
Mr Blair also recently met Democratic Unionist leader Ian Paisley whose party has called for the removal of allowances and privileges at Westminster from Sinn Fein's four MPs.