Irish Ferries and Siptu are to return to the Labour Court today in a final bid to resolve their dispute over the company's plan to outsource crewing on its Irish Sea routes.
The court is expected to issue a recommendation on the matter shortly, as the sides have been unable to reach agreement in talks over the past few weeks.
The row over the company's plan to replace up to 540 unionised seafarers with cheaper labour from eastern Europe has threatened to scupper talks on a new partnership deal.
Unions have decided not to enter talks on a successor to Sustaining Progress in the absence of Government guarantees on action to defend employment standards and prevent exploitation of migrant workers.
Their stance arose directly from the dispute between Siptu and Irish Ferries.
The company has defended its plan, claiming that outsourcing jobs is the only way to ensure it remains competitive. In newspaper advertisements last week, it said that 95 per cent of its competitors were already outsourcing employment.
This was dismissed as a "half truth" by Siptu official Paul Smyth, who said the two main ferry companies on the Irish Sea were Irish Ferries and Stena Line.
"Stena Line is not doing what Irish Ferries proposes to do and has said it has no intention of going down that route," he said.
Unions have also condemned the fact that the agency workers hired to replace existing seafarers would be paid just €3.60 an hour, less than half the Irish minimum wage. In response, Irish Ferries said those being hired would live on board with accommodation, food, travel and other living expenses paid for.
Up to 10,000 people marched through Dublin last week in protest at the company's plans and to highlight concerns about displacement of jobs in other areas of the economy.
Ictu general secretary David Begg told a subsequent rally it would take a worker on €3.60 an hour two and a half weeks to earn what Irish Ferries chief executive Éamonn Rothwell earned in an hour. An Irish Ferries spokesman said Mr Rothwell's income was "quite modest" compared to that of other people running companies of the same size.