OIL and gas services supply firm Schlumberger is proposing to close its Newtownabbey plant with the loss of more than 220 jobs.
The multinational has had a base in Northern Ireland for almost 60 years.
It is understood staff were informed this morning and sent home from work.
Schlumberger is the world's leading provider of technology for reservoir characterisation, drilling, production, and processing to the oil and gas industry. The firm works in 85 countries and employs around 100,000 people worldwide.
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Trade union Unite said the proposal is an attempt to lower costs at workers' expense.
In a statment Schlumberger said: "Due to the current prolonged downturn in the oil and gas industry, Schlumberger's manufacturing plants globally are underutilised and the company is considering a proposal to cease manufacturing, assembly and test activities in its Belfast plant during 2018."
"We completely understand the impact of this announcement on our employees and the local community.
"This is only a proposal at this stage and we will be conducting consultation with the union and our employee representatives to make every effort to try and mitigate as much as possible the impact on our employees.
"The oil and gas industry is going through the most severe downturn of the past 30 years with operators significantly reducing their investment.
"This is severely impacting technology services companies like Schlumberger.
"Between 2014 and 2016, Schlumberger's revenue was reduced by nearly half and unfortunately, we do not see yet any sustainable recovery.
"This scenario means, that to adapt to the new realities of the market, we need to restructure our production footprint."
Unite regional industrial officer Susie Fitzgerald said the company was a key employer in Newtownabbey and the announcement was "another hammer blow" for the manufacturing sector.
“Unite will be seeking urgent meetings with Schlumberger to demand answers as to how they can justify a decision to close their site in Northern Ireland when the crunch affecting the oil and gas sector is a global one and affects all locations equally. We are aware that they have transferred much activity formerly conducted onsite at Newtownabbey to other, low-cost locations, including China.
“We are concerned that the company’s global corporate management are attempting to use the downturn in the oil and gas sector as cover to further outsource jobs to low cost alternative locations. If so we will be rejecting their logic."
