Supporters of the so-called "Colombia Three" refused an offer of state security for the men because of fears of collusion with right-wing forces.
Colombian official sources said that James Monaghan (58), Martin McCauley (41) and Niall Connolly (38) were offered a military escort on their departure from La Modelo prison in Bogota but this was turned down.
The spokeswoman for the Bring Them Home Campaign and Sinn Féin member of the Northern Assembly, Ms Caitríona Ruane told The Irish Times last night: "We organised the security ourselves."
Ms Ruane said the basis for this decision was the experience of collusion in Northern Ireland and reports about activities of a similar nature in Colombia. She refused to specify the nature of the security provided. The men were brought from the prison in two private sports utility vehicles and a pick-up truck.
She said the three Irishmen had been brought to "a safe, undisclosed location" after their release from prison at 11.40 p.m. Irish time on Tuesday night, but made no comment on reports that they were taken to a private apartment arranged for the purpose in advance.
Ms Ruane expressed bitter disappointment that the appeal tribunal had explicitly refused permission to the three men to return to Ireland while their appeal was being heard. "We believe it is unjust that they have to remain in Colombia during that time."
She called on the Taoiseach, Mr Ahern, to renew pressure on Colombia's President Uribe to speed up the appeal process and she urged the Colombian judiciary to expedite the appeal.
The three men were found not guilty on April 26th last of training the FARC rebels in bomb-making techniques, but convicted on the lesser charge of using false passports.
An appeal against the verdict was lodged by the Colombian Attorney-General's office and defence lawyers petitioned the three-member tribunal to allow the men to go back to Ireland while the appeal was under consideration.
But this week the appeal tribunal, headed by Ms Marta Lucia Tamayo, turned down the men's request to leave the country. It is understood the men were also ordered to vacate La Modelo prison on the basis that the risk to their lives outside the jail was medium to low.
However, Ms Ruane said: "While the men remain in Colombia their lives are at risk." She was "confident" they would win their appeal.
There were unconfirmed reports that flight arrangements had been made to transport the men home to Ireland overnight, if the appeal judges allowed them to leave Colombia, and that emergency travel documents were also available to ensure their safe return home.
A sum of approximately €17,000 was advanced by the Department of Foreign Affairs and paid over to the Colombian authorities several weeks ago.
This was the equivalent of a bail payment and the Bring Them Home Campaign is due to refund the "loan" to the Department as soon as possible. The purpose of making an early payment was to expedite the men's departure if they were allowed leave the country.
The Minister for Foreign Affairs, Mr Cowen, was expected to speak about the case last night with his Colombian counterpart, Ms Carolina Barco, or her deputy.