Steel-maker Tata said today that it will cut 900 jobs and close 12 of its sites in Britain.
Five-hundred of those will come from its Port Talbot plant in unemployment-racked south Wales.
The firm said getting rid of the workers would make it more competitive.
The job losses at Tata follow 12,500 recent redundancies at Vion, 900 at Hovis bread-maker Premier Foods, 140 at Standard Life, 2,600 at Turning Point, 735 at Comet and 1,300 at Newcastle City Council.
Unite general secretary Len McCluskey said: "The news at Tata rounds off a dark seven days for the UK economy.
"Tens of thousands of people will be facing a Christmas of uncertainty thanks to the jobs carnage wrought by this government's bungling handling of the economy."
Steelworkers' union Community general secretary Michael Leahy said he wants an urgent meeting with Tata bosses "to ensure our principle of no compulsory redundancies is upheld."
A Welsh government spokesman called it "very disappointing and a massive blow.
"Tata's decision reflects the serious and ongoing challenges faced by manufacturing industries."
Shadow Welsh secretary Owen Smith said: "I am deeply concerned at the government's intransigence in the face of repeated calls from companies such as Tata about the challenges that high energy costs and uncertainty over government policy are posing."
Tata said it will restart one of two blast furnaces at Port Talbot in the first quarter of next year as part of a £250 million investment programme.
Its European chief executive Karl Kohler said: "We will be working with our trade unions and government at a national and local level."
The company employs 19,000 people in its British steel business and limply claimed that it was committed to investing in it "to help create long-term stability."