Sinn Féin leader Mr Gerry Adams said he would decide today whether to go to the United States to answer questions about alleged links between the IRA and Colombian guerilla group FARC.
He said senior party members would meet in Belfast today to decide if he should travel to the House of Representatives in Washington for the hearing on Wednesday.
Mr Adams said he was being advised not to go despite repeating that it was his "instinct" to attend.
He said: "The lawyer of the three men on trial in Colombia believes that a hearing which deals with them or their case would be prejudicial to them having a fair trial.
"This increasingly appears to be little to do with Ireland, to be all to do with those in Colombia who want funding for their own purposes".
The House of Representatives International Relations Committee would be informed of the decision before it is made public, Mr Adams said.
Earlier, the Bring Them Home Campaign - representing the three arrested men, Mr Niall Connolly, Mr James Monaghan and Mr Martin McCauley - also raised fears that the hearings would prejudice a fair trial.
The men are being held on suspicion of helping train FARC guerrillas opposed to Colombia’s US-backed President Mr Andres Pastrana.