Socialist TD Joe Higgins accused Irish Ferries of an "act of high-seas piracy", following the introduction of what he called "storm trooper-type security" on the company's vessel, Isle of Inishmore, at Pembroke in Wales.
The deputy called on the Government to make a statement in the wake of the move on the vessel yesterday, as part of the company's plan to replace unionised employees with cheaper workers from eastern Europe.
Mr Higgins, who suggested similar action was taking place on the Ulysses at Holyhead, intervened yesterday evening during Dáil transport questions.
He called on Minister for Transport Martin Cullen to make a statement "on the Government's attitude to this incredible act of high-seas piracy on foot of Irish Ferries' campaign to sack 540 workers and replace them with the most exploited labour from eastern Europe, and taking this unprecedented action today on the high seas in Pembroke and in Holyhead".
Earlier the Dublin West TD accused Taoiseach Bertie Ahern of surrendering to Irish Ferries' controversial outsourcing plan, following his comments that the Government could do "no more" on the issue.
He claimed the Taoiseach had "openly raised the white flag before Irish Ferries' slave labour plans".
Mr Higgins asked Tánaiste Mary Harney "is this it? Is the exploiter now to run riot?"
Ms Harney said Minister for Enterprise, Trade and Employment (Micheál Martin) "is examining general employment protection legislation".
Mr Ahern said on Wednesday he did not think the dispute at the company was going to be resolved after Irish Ferries refused to accept a Labour Court recommendation.
The company plans to replace up to 543 workers with agency workers, who will be paid €3.60 an hour.
Mr Higgins called for an amendment to the Fisheries and Maritime Jurisdiction Bill to "outlaw these modern-day slavers plying Irish and European waters".
The Bill aims to consolidate existing sea fisheries law, but fishing communities claim it discriminates against Irish fishermen, and it has provoked strong criticism from all sides in the Dáil.
During the ongoing debate Jim O'Keeffe (FG, Cork South-West) said that under Irish legislation "fishermen are fined amounts by the courts that are 10 times those payable on conviction by their continental counterparts".
He said: "We must have sanctions for breaches of the law, but let us not put our fishermen to the wall and sink them beneath the waves, because we are not prepared to change a system which is totally out of sync with the needs of the industry."
Denis O'Donovan (FF, Cork South-West) highlighted a letter from a solicitor who defended a fisherman whose offence was not filling in his vessel's log book. But he suffered penalties totalling €40,000. If the case happened elsewhere in the EU, an administrative fine would be imposed.
"The fines and penalties detailed in the Bill lack proportionality and must be reduced and changed," Mr O'Donovan insisted.
