The IRA was to be paid between €20 million and €30 million to train Colombian Farc guerrillas in how to use explosives, Minister for Justice Michael McDowell has said.
Intelligence in his possession indicated that had the training gone ahead as planned and the "Colombia Three" not been detected by the authorities in Colombia, the IRA was to be paid "between €20 million and €30 million" by Farc guerrillas.
He did not disclose the source of the intelligence on which he was basing his comments.
Mr McDowell has previously stated that the "Colombia Three" - Niall Connolly, Martin McCauley and James Monaghan - had travelled to Colombia in August 2001 to train Farc rebels in exchange for a large sum of money for the IRA.
However, the estimated value of the arrangement has never been disclosed before now.
Mr McDowell has also said the monies that were to be paid by Farc had been raised by the group's involvement in the global cocaine trade.
The "Colombia Three" were convicted in Colombia of entering the country on false passports in 2001.
An acquittal on the more serious charge of training Farc guerrillas was later overturned by an appeal court, and a 17-year sentence imposed. The men jumped bail and reappeared in Ireland last August.
Last December Mr McDowell linked three other men to the plot, including former journalist Frank Connolly, a brother of Niall Connolly and director of the Centre for Public Inquiry (CPI). When the controversy broke the billionaire Irish-American philanthropist Chuck Feeney withdrew his financial backing from the CPI.
In a reply to a parliamentary question at the time, Mr McDowell said that "prior to the arrest of the so-called Colombia Three in August 2001, authorities had established that three Irish people also entered Farc-controlled territory on false passports, and one of those was Frank Connolly". The other two men, he said, were Niall Connolly and convicted IRA member Pádraig Wilson.
When asked during an interview on Newstalk 106 yesterday if he was confident that prosecutions would follow arising from Mr Connolly's alleged use of a false passport in Colombia, Mr McDowell said: "It's not an offence under Irish law to have possession of a false passport in Colombia. It [travelling on a false passport] could be an offence if the evidence was available to the Director of Public Prosecutions provable beyond all reasonable doubt that he had such a passport."
He denied that the account he had given about Mr Connolly's alleged movements in Colombia and the IRA plans to train Farc guerrillas lacked credibility.
He said it was not possible to think of "an explanation which is more credible" than the "intelligence-based explanation" he had given.