Corus is to shed 236 jobs as part of a shake-up at its steelworks in Scunthorpe.
Union leaders branded the announcement a disgrace, accusing the company of paying lip service to the concept of consultation.
When chief executive Philippe Varin took over last year, he said there would be a new era of negotiation with the workforce.
After years of leadership under Sir Brian Moffat during which thousands of jobs were lost without consultation, union officials believed Mr Varin had changed the company's culture.
But the Iron and Steel Trades Confederation (ISTC) said there had been little union involvement during the latest round of cuts.
Eddie Lynch, assistant general secretary of the ISTC, said: "The union believes the way that they have handled the announcement is a disgrace.
"Once again, Corus has shown that they pay only lip service to the concept of consultation.
"Telling union representatives of proposed job losses once the decision has been taken and a matter of hours before an announcement is simply not acceptable."
The job losses were announced as the company said it was investing £32m in modernising its steel rod and plate-making plant in North Lincolnshire. Eighty of the jobs will be lost as a result of this in the next two years.
A further 156 staff at Scunthorpe's heavy section mill will be going when the site closes later this year.
Corus said the moves, part of the group's overall restructuring programme, were positive steps to significantly improve the profitability and competitiveness of the company.
Andrew Page, managing director of Corus Construction and Industrial, said: "We are taking action to focus on those areas that offer us scope for growth and profitability."
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