Sinn Fein has accused the Naval Service of discrimination in barring two of its members from working at the Haulbowline naval base in Co Cork.
The two roofers, Mr Jonathan O'Brien, a Cork city councillor, and sub-contractor Mr John Callaghan, were told not to return to work on the refurbishment of a naval building at the base last week after being denied security clearance.
Sinn Fein ardcomhairle member Mr Martin Ferris condemned the move, which he pointed out came as the Taoiseach, Mr Ahern, was encouraging the party to support the security forces in the North.
"At a time when Bertie Ahern is urging Sinn Fein to join the police boards in the six counties, the Navy in the 26 counties are discriminating against members of Sinn Fein," he said.
He said the party was determined to have the two men reinstated and given an apology.
Mr O'Brien and Mr Callaghan said they were given no explanation for the decision, despite requests made through union representatives.
"I honestly cannot think of any reason, other than our political allegiances. It wasn't to do with the quality of our work," Mr O'Brien said.
"But if it was a matter of security clearance, I can't understand why we were allowed on the site for a week and a half. And I don't understand why I'm a security risk. I have never been arrested - never even been in the inside of a Garda station - and neither has John," he said.
Defence Forces' spokesman, Comdt Kieran McDaid, said he could not comment on the reasons for the decision to remove the two men from the base but said they were mistaken if they believed they had security clearance.
Mr Callaghan said the news was broken to him through the main contractor on the site, who also received no explanation. "They had no problem with a third man who was working with us but as I'm employing him he has had to go too."
Mr O'Brien, who was co-opted on to Cork Corporation early last year, said he feared he would now lose other work. "This is going to affect my character and in this business, reputation is everything."