Irish police are satisfied that cash found during raids in the Irish Republic is linked to the Northern Bank robbery, Bertie Ahern has said.
Mr Ahern made the comments in an interview for the BBC
Police seized almost £3m - £60,000 of it in Northern Bank notes - during raids last month linked to alleged money laundering in Dublin and Cork.
The IRA has been blamed for the £26.5m raid at the bank's Belfast headquarters on 20 December. The IRA denies this.
Mr Ahern said police were sure the cash "was part of the haul from the north".
The Irish prime minister told the BBC's Hearts and Minds programme: "Before I went to the United States, the position of the gardai (was) that they had done an enormous amount of forensic tests.
Millions were taken from the vaults of the Northern Bank last December
"But they are quite satisfied - professionally, absolutely and totally satisfied - as I understand it, that that money was part of the haul from the north."
Mr Ahern added that while tests were still ongoing, the police assessment was quite clear.
He said that it meant the IRA was indeed behind the bank robbery and now had a considerable amount of money which it did not have previously.
Earlier this month, Northern Ireland's Chief Constable Huge Orde said there were "clear indications" money found in Cork came from the Northern raid.
The bank is replacing £240m of its notes - exchanging old Northern Bank money for notes with a new design and colour - following the robbery.
Police on both sides of the border have said they believe the IRA was behind the robbery.
As a result of the claims, Sinn Fein MPs are to be stripped of £400,000 in parliamentary allowances.