Bombardier Aerospace is cutting 600 jobs at its Northern Ireland operations.
It said the move was in response to “extraordinary industry interruptions and challenges” caused by the coronavirus pandemic.
The cuts are on top of the 2,500 redundancies across the Canadian firm’s global operations announced last week.
Bombardier employs about 3,600 people across several factories in greater Belfast.
It is understood that 400 staff and 200 agency staff will lose their jobs.
“We deeply regret the impact this will have on our workforce and their families, but it is crucial that we resize our business in line with market realities in these unprecedented circumstances,” Bombardier said.
Economy Minister Diane Dodds said she would work with those who “have received devastating news and those who will potentially be impacted”.
She said she understood “the significant distress today’s announcement will cause”.
“I understand the 90-day redundancy will go into action today and as this progresses of course my department will organise help to those who are impacted both in terms of any other employment opportunities or retraining and up-skilling,” she added.
Analysis: Aerospace challenges ripple into NI
By John Campbell, BBC News NI economics and business editor
The global aerospace sector is reeling from the impact of coronavirus.
Airlines are in a scramble to conserve cash and even those who survive will not be in a position to invest in new fleets.
Major aerospace suppliers like Rolls Royce have already announced thousands of jobs losses, so it was inevitable that would ripple into Northern Ireland.
The local aerospace sector has been a success story in recent years, supporting thousands of well-paid jobs.
Now it’s facing its biggest challenge since 2001.
Having reviewed its operations in Belfast, Bombardier said it had to adjust the workforce “to align with market demand for the remainder of this year and through 2021”.
Bombardier’s Northern Ireland operations are currently in the process of being sold to the US firm Spirit AeroSystems.
Bombardier’s Belfast operations were wound down at the peak of the pandemic, with about half of staff believed to be back at the factory.
The company said it expected business jet deliveries to be down 30% industry-wide.
Last May, the company said it was putting its Northern Ireland operation up for sale as part of a reorganisation of the business.
Susan Fitzgerald, from the union Unite, said the cuts were a huge blow “to Bombardier’s workforce, their families and the economy of Northern Ireland as a whole”.
She called for urgent action from the Northern Ireland Executive.
Paul Everitt, chief executive of the ADS aerospace industry group, said: “Businesses in the whole of the UK aerospace industry are now facing difficult decisions affecting their workforces.
“This is an unsettling time for workers and their families.”
This is the second big round of redundancies in the Northern Ireland aerospace sector in a matter of days.
Last week Thompson Aero Seating in Portadown said it was cutting as many as 500 jobs.