The Taoiseach Mr Bertie Ahern has said he would not enter coalition government with the Sinn Fein while the IRA retained some of its arms.
Growing support for Sinn Fein in the Republic has led to speculation it may hold the balance of power after a general election due by June next year.
But in an interview published in the Sunday Business Posttoday, Mr Ahern said the IRA - which decommissioned some of its weapons in October - had not done enough for Fianna Fail to drop its objection to sharing power with Sinn Fein.
Mr Ahern said the question was that of the continued existence of an illegal private army associated with a political party.
Until that position is resolved, it would not be tenable for Sinn Fein to participate in an Irish Government, as the constitution recognises only one army and one police force in this jurisdiction, he said.
A poll published in the Irish Independentnewspaper yesterday suggested Mr Ahern was on course to become the first Taoiseach since 1969 to be elected for a second term.
Mr Ahern also said in the interview his government would continue its legal efforts to close Britain's nuclear reprocessing plant at Sellafield.