SIPTU has won a temporary injunction preventing Irish Ferries from going ahead with its compulsory redundancy plan.
The High Court injunction will remain in place until next Wednesday when Irish Ferries are expected to come to court to argue their side of the case.
The interim order prevents Irish Ferries from issuing compulsory redundancy notices or otherwise terminating the employment of any SIPTU member pending a full hearing.
Irish Ferries earlier rejected a second invitation to attend the Labour Court to try to resolve the row over redundancy plans.
The company plans to replace almost 550 staff members with cheaper agency workers from Eastern Europe.
The company says it is prepared to attend the Labour Court on Monday to deal with specific procedural matters. However, it is refusing to discuss the general redundancy issue.
By then, however, Sunday's deadline for workers to accept the redundancy deal would have passed.
Labour Court Chairman Kevin Duffy has informed the company that he will not defer today's session until Monday, because of the urgency of the situation.
Meanwhile, Irish Ferries claimed that it had 450 signed acceptances from staff opting to take redundancy.
A spokesperson said only six workers had opted to stay on lower pay and conditions.
He said the remainder are undecided.
However, unions have disputed these figures, accusing management of trying to stampede workers into giving up their jobs.
Unions 'not blameless': Dempsey
The Minister for Communications, Marine & Natural Resources said today unions were not totally blameless in the row.
Noel Dempsey said that the company should go to the Labour Court but added that the record of the unions in Irish Ferries was not particularly exemplary.
He said he was taking legal advice on allowing Irish Ferries to re-flag their vessels.
He said his instinct was not to allow the re-flagging but he said he felt this might not be possible.
