(Reuters) - Ukraine's biggest steelmaker Metinvest said on Friday its enterprises would never operate under Russian occupation and that Ukraine had lost access to 30% to 40% of its metallurgy production capacity in the besieged port city of Mariupol.

       It told Reuters in a statement that Ukraine, one of Europe's biggest suppliers of iron ore, had already more than halved its iron ore production due to the invasion that Russia launched on Feb. 24.

       (Reporting by Natalia Zinets; editing by Guy Faulconbridge)