In a major escalation of the dispute at Irish Ferries, SIPTU has served indefinite strike notice to take effect from Monday.
None of the company's ferry services operated today due to the unions' 24 hour stoppage over management plans to outsource 150 jobs on its Rosslare to Cherbourg route.
The union says it is escalating its action because the company has proceeded to hire agency workers on the MV Normandy, which is currently berthed in Belfast for maintenance work.
Earlier this year, Irish Ferries agreed cost savings of over €3m with SIPTU and the Seamen's Union of Ireland.
Now the company wants to replace 150 staff on the Rosslare to Cherbourg route with workers outsourced from an agency - cutting payroll costs by a further €3.5m a year. Most staff have accepted a redundancy package and the rest will be redeployed.
But SIPTU fears that that once conceded, the principle of outsourcing will spread to other routes.
The company condemned the strike, warning it would divert customers to competitors because of uncertainty about the service.
The Irish Road Hauliers Association described the industrial action as grossly irresponsible - coming at the peak freight period before Christmas.
