The Taoiseach Mr Ahern today ruled out the possibility of Fianna Fáil forming a coalition government with Sinn Fein.
Speaking on the BBC's Breakfast with Frost programme, Mr Ahern said Sinn Féin would have to sever their connection with the IRA before such a coalition could even be considered.
"I have made our position very, very clear, In our constitution there can only be adherence to one police force one army and until Sinn Fein make their position unambiguously clear then that is not possible and that is not going to be possible for some time," Mr Ahern said.
"Though I do acknowledge that Gerry Adams and Martin McGuinness and others have clearly stated that it is their intention to move their political movement totally away from the past and totally away from their associations or connections with the IRA.
"In actual fact I think their stated position is that there will be no IRA."
Sinn Féin were also urged to sign up to Northern Ireland's Policing Board, which Mr Ahern said had "performed well".
"I think ultimately if we are to have proper policing with the respect of the community, it's necessary in any society that the community supports the police service.
Mr Ahern said he hoped their support would be forthcoming after a review of policing reforms which is due to start in April.
"That's meant to take about six months and the other side of that, it is hoped that there could be some amending legislation.
"Somewhere around that, I hope that Sinn Féin would take the opportunity to come in, because I do think ultimately it is vital that everyone representing nationalist and republican, loyalist and unionist are part of the police service.