Defence giant BAE Systems is to axe 1,100 jobs and close one of its sites, unions said today.
The Confederation of Shipbuilding and Engineering Unions (CSEU) said the news was "bitterly disappointing" for workers and local communities.
The cuts will affect a number of sites, including Woodford in Cheshire, which will close, said the union.
The CSEU's general secretary, Hugh Scullion, said: "This is bitterly disappointing news for the staff and for the local communities which rely on these jobs.
"This is particularly true in the case of the proposed closure of Woodford. The CSEU will work constructively with the company to keep redundancies to a minimum and ensure no compulsory redundancies.
"The CSEU believe there is still an opportunity to extend production at the Woodford site."
BAE later announced that, following a detailed review of its current and future business levels, it had started consultation on the potential closure of Woodford and cuts at another three sites, with the loss of 1,116 jobs.
The firm is planning to close the Woodford site at the end of 2012, on completion of the Nimrod MRA4 production contract, with the loss of 630 jobs.
A further 205 jobs will be lost at Samlesbury in Lancashire, 170 jobs at Warton in Lancashire and 111 jobs at Farnborough in Hampshire.
The company said in a statement: "It has been clear since 2003 that the Woodford site had little future beyond the end of Nimrod MRA4 production, and the workforce has been kept informed since that time.
"Despite strenuous efforts to achieve further Nimrod production work, there has been none forthcoming. It is intended that there will be a phased run-down of the site in line with the production programme.
"At Samlesbury, the potential job losses are in the manufacturing function and are associated with the end of Airbus work currently undertaken by BAE Systems for Spirit AeroSystems.
"At Warton, the potential job losses are in the manufacturing and operations areas as work on the Nimrod, Tornado and Hawk programmes decreases.
"At Farnborough the potential job losses are in the Harrier business. The job losses are as a result of a downturn in Harrier upgrade work over the next few years."
Kevin Taylor, managing director of BAE's Military Air Solutions arm, said: "Whilst we regret having to make this announcement, we have to ensure we are the right size and shape to remain competitive and meet our customer's requirements in the future.
"We will work with our employees and their representatives to explore ways of mitigating these potential job losses and we will do everything necessary to deal with the potential job losses and closure of Woodford in a professional way and support our people throughout this process."
Conservative MP Nigel Evans, whose Ribble Valley constituency includes the Samlesbury plant, said: "Job losses at any time are disappointing but they are particularly felt during periods of economic difficulty.
"I sincerely hope that there will be no compulsory redundancies at BAE and that the company looks seriously at other job options on site or in other parts of the company so that any losses are minimised.
"In terms of Samlesbury, it seems that a large number of the jobs are going because Spirit Aerosystems, for whom BAE have worked on the Airbus, are relocating their labour abroad.
"This should send a warning signal to the Government that more work needs to be done to keep manufacturing in the UK. These are difficult times for many companies and the Government must ensure that we retain British industry."
Speaking at the Vauxhall plant in Ellesmere Port, Cheshire, today, Prime Minister Gordon Brown said: "Any redundancy, any job loss is a very difficult situation. It's a personal tragedy for families.
"I know that British Aerospace have got jobs that are based on the Nimrod, I know that production ceases at a certain point. I think that has been known for some time and I think that is the main area of job loss.
"We will do everything in our power to help those people who are working in British Aerospace in the years ahead when these changes are taking place to help find new jobs.
"That is why we are backing thousands of companies in this area with cashflow, we are helping them with money at the moment and we will continue with whatever we can do to help them train for new jobs."