Aug 11 (Reuters) - Seven workers were killed at a Ukrainian steel plant on Tuesday during a Russian attack on the southeastern city of Zaporizhzhia in which President Volodymyr Zelenskiy said Moscow used North Korean ballistic missiles. The ‌Zaporizhstal plant was forced to suspend production after being hit as Russia pummelled Zaporizhzhia with Zircon hypersonic missiles, ‌guided aerial bombs and ballistic missiles supplied by Pyongyang. Russia's ⁠defence ministry said Russian forces had struck a metallurgical plant in Zaporizhzhia that produces flat-rolled steel which it said was used by the Ukrainian military. Moscow did not ​immediately say whether it had used North Korean missiles in the attack on ​Zaporizhzhia. Russia has fired scores of North Korean ballistic missiles at Ukraine since late 2023, but the deployment of North Korean missile forces would be an expansion of the already extensive military cooperation between Moscow and Pyongyang.