As demonstrators marched, P&O ship European Causeway remained detained in Larne, County Antrim, for being 'unfit to sail'.
Two more P&O ships face checks next week, Sky News understands.
"The vessel will remain under detention until all these issues are resolved by P&O Ferries. Only then will it be reinspected."Trade unionists rallied outside the P&O terminal at Dublin Port
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