Russian forces seized full control of the eastern Ukrainian city of Sievierodonetsk, confirming Kyiv's biggest battlefield setback for more than a month, following weeks of some of the war's bloodiest fighting.

A commander of an elite unit of Ukrainian marines has told Sky News the majority of his best trained troops have been injured or killed. Speaking near the frontline, south of the city of Severodonetsk, company commander Oleksandr said a core of experienc...