The International Transport Workers' Federation (ITF) has condemned the move by Irish Ferries to reregister one of its vessels, the MV Normandy, to the Bahamas.
Mr Tony Ayton, an ITF inspector, said it meant that any worker taking up duties on the vessel would not benefit from the Republic of Ireland's worker protection legislation, including the right to a minimum wage.
Mr Alf McGrath, director of human resources at Irish Ferries, said he had "no comment whatsoever" to make on the issue.
The ITF "does not want to jeopardise the current talks at the Labour Relations Commission aimed at resolving the dispute between Irish Ferries and the trade unions", said Mr Ayton. "Nevertheless, we must condemn this action by Irish Ferries management."
Talks between the two sides are continuing at the LRC after SIPTU called off a 10-day strike over company plans to outsource crew on its Rosslare-Cherbourg service from next year, on which the Normandy operates.
The indications are that the Normandy is the only vessel affected. Mr Ayton said: "If it was only the Normandy we wouldn't be happy, but the experience is that when bad practices like this are introduced they grow."
