Workers at the Harland and Wolff shipyard are fighting on to save it, even as the historic firm enters administration.
The legal process at the High Court in Belfast is expected to be completed later.
The move could put 125 jobs at risk.
The workers and trade union officials held a conference call with Secretary of State Julian Smith on Tuesday afternoon.
Unite regional organiser Susan Fitzgerald said the workers are “digging in”.
“We raised points that the workforce are here, they are digging in, this is a viable operation, there are contracts out there waiting to be won, work waiting to come in and on the basis of an intervention from this Government, that work could start straight away,” she said.
“We made it clear to the Secretary of State that the Government needs to intervene now, they need to offer a lifeline to the workers here by re-nationalising this shipyard.
“We also made it clear that it would cost more money to close it than it would to save it, so it’s not a moral argument we are making, there is a hugely economical and viable argument that we are making here.
“The workers who were on the call made it clear to Julian Smith that he needs to come back with some answers.
“He indicated that he would go off and investigate the points that we had raised and come back to us. There is a further conference call set up for later this week.”
She added: “The workforce here are one of the most defiant, capable and committed groups of workers that I have ever met. If they have made the decision to stay in here until they win, well then that’s what will happen.
“This workforce is going nowhere.”
In a statement a spokesman for administrators BDO Northern Ireland said: “BDO Northern Ireland partners Michael Jennings and Brian Murphy have been appointed as joint administrators of Harland and Wolff.
“Founded in 1861, the Belfast-based company has in recent years specialised in wind energy and marine engineering projects.
“After a long sales process, in which a buyer could not be found, the business has been unable to continue trading due to having insufficient funds following the recent insolvency of its ultimate parent.
“The team at BDO have engaged immediately with Harland and Wolff employees and other stakeholders to take all necessary steps to ensure they are supported throughout the administration process.”
Harland and Wolff workers voted on Monday to continue their round-the-clock occupation of the site.
Ms Fitzgerald warned then that no administrator would be able to drive on to the shipyard site without the permission of the workers.
“No-one moves on to that site or off that site unless the workforce, who are running that site, agree to it,” she said.
Harland and Wolff, one of Northern Ireland’s most historic brands, is facing closure after its trouble-hit Norwegian parent company Dolphin Drilling failed to find a buyer.
Workers have occupied the site since last Monday as part of a high-profile campaign to save the yard.
They have called on the Government to step in to rescue the operation, potentially through nationalisation, but the Government has declined to intervene, insisting it is a commercial issue.
Officials insist that EU state aid rules limit the scope to offer financial support through public funds.
On Monday evening, a Government spokesman said Mr Smith “has made it clear that he will continue to do everything he can to secure the future of this historic site and ensure workers’ interests are protected during this difficult time”.
The shipbuilder, whose famous yellow cranes Samson and Goliath dominate the Belfast skyline, employed more than 30,000 people during the city’s industrial heyday, but now the workforce only numbers around 125.
It has diversified away from shipbuilding in the past two decades and until recently had primarily worked on wind energy and marine engineering projects.
Famed for building the doomed White Star liner Titanic, which sank on its maiden transatlantic voyage in 1912 after striking an iceberg, Harland and Wolff was one of the UK’s key industrial producers during the Second World War, supplying almost 150 warships.
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