A firm which provides computer services to companies across the UK has announced plans to cut 640 jobs.
Computer Sciences Corporation (CSC) started a formal 90-day consultation with unions today, saying in a statement: "This action is necessary because the IT services market is changing, and our customers want competitive, new services with different contract and delivery models."
Unite said the announcement was a "body blow" which had left employees feeling "devastated".
The company continued: "Through voluntary redundancies and redeploying people within other parts of our business, we hope to achieve a significant reduction without the need for compulsory redundancies. Where this is not possible, we will provide support to help ensure that anyone leaving the business does so in the best possible position.
"Our employees will naturally be concerned during this period of uncertainty, which is why we have initiated employee briefings to help them through this difficult situation.
"CSC remains fully committed to the UK market. We are confident that these carefully targeted and managed reductions will not impact the overall quality of service we provide to our customers."
Unite said the news will mean that 1,100 job losses have been announced by CSC since February.
Following several weeks of consultation over a reduction of staff working on an NHS contract, today's move had come "totally out of the blue", according to Unite.
National officer Kevin O'Gallagher said: "This announcement of a further 640 job cuts has dealt our members a severe body blow and left them absolutely devastated.
"We have put forward a detailed plan which will avoid any compulsory redundancies in the company, however these plans have not been taken up and CSC is insistent on issuing compulsory redundancy notices despite receiving sufficient number of volunteer requests to leave the company.
"With the full support of our membership, Unite is determined to avoid any compulsory redundancies, which are clearly unnecessary and in the main to enhance the profits of its American shareholders. We now owe it to our members to do everything in our power to support them during this very uncertain time and fight these job cuts."
Last week, Unite members from CSC's Chesterfield, Chorley, Leeds and Solihull sites took part in lunch-time protests over jobs.