The venerable steel producer, which has been struggling against high energy prices at home and growing competition from abroad, is the latest company in Europe to cut its work force.

Thyssenkrupp's steel business plans to cut some 40% of its workforce over the coming years, it announced on Monday in the latest painful overhaul of a German industrial giant, with workers promising fierce resistance.

The IG Metall trade union has made clear it will support the planned attacks—provided, as with the cutbacks of recent decades, plant closures and compulsory redundancies are ruled out.