Ulster Unionist sources confirmed their party leader met Colombian vice president Francisco Santos on the fringes of the Earth Summit in Joannesburg, South Africa.
“The discussions dealt with republican involvement in Colombia. David Trimble also discussed the upcoming trial,” a source said.
Republicans Martin McCauley, James Monaghan and Niall Connolly, have been held since last August by the Colombian authorities after they were arrested attempting to leave the country following a visit to a zone controlled by the Marxist FARC militia.
Taoiseach Bertie Ahern said he was aware of what Mr Trimble was doing and speculated he was trying to find out from the Colombians what the three men were up to. Colombian authorities have alleged the three men trained FARC guerrillas in bomb-making techniques and that IRA technology has been deployed to deadly effect in the South American country’s civil war.
They allege mortar-style devices similar to those used by the Provisional IRA in the North during the Troubles have been used by FARC and there has been a shift in tactics used by the organisation.
Supporters of the three detained men have protested their innocence.
They are expected to go to trial in October.
Last month, Sinn Féin clashed with the country’s chief prosecutor Luis Camilo Osorio after he alleged the IRA had been testing weapons in the Colombian jungle and had shared techniques used in recent FARC mortar bomb attacks.
His comments were branded a “disgrace” by Sinn Féin national chairman Mitchel McLaughlin who claimed they prejudiced the chances of a fair trial.
The Foyle MLA called on the chief prosecutor to resign.
The arrests of the three men sent shock waves through the North’s peace process, unsettling David Trimble’s Ulster Unionist Party.
The First Minister faces a crunch meeting of the UUP’s ruling council on September 21 to discuss whether they should remain in the power sharing government with Sinn Féin amid allegations of IRA involvement in Colombia, the break-in at the top-security Castlereagh police station in March and recent street clashes in sectarian flashpoint areas of Belfast.
Mr Trimble said in Johannesburg that the meeting was his first opportunity to touch base with the new administration in Colombia.
He was criticised by Sinn Féin for meeting the Colombian vice president. North Belfast MLA Gerry Kelly accused him of “deliberately prejudicing the right to a fair trial” for the men.