Ukraine's largest steelmaker, Metinvest said on Wednesday steel and coke assets in territory controlled by pro-Russian separatists had been seized by rebels.
"Metinvest does not expect any such seizure to have a negative effect on the implementation of its debt restructuring," the company said in a statement.
Metinvest's bond holders and banks agreed a restructuring last month.
Metinvest is part of the business empire of Ukraine's richest man, Rinat Akhmetov. Earlier on Wednesday, Akhmetov's DTEK Energy also said its largest mines in separatist regions had been taken under rebel control.
Metinvest said Yenakiieve Iron and Steel Works was among the seized assets.