<p>Russia's army said Saturday that some Ukrainian military units were withdrawing from the key city of Severodonetsk in eastern Ukraine.</p>.<p>"Some units of the Ukrainian army, having suffered critical losses during fighting for Severodonetsk, are pulling out towards Lysychansk," Severodonetsk's twin city, which sits just across a river, the defence ministry said in a statement.</p>.<p>It added however that some Ukrainian fighters remained in the city.</p>.<p>"The Ukrainian authorities, having realised that it was impossible to resist further and to hold on to the industrial zone of Severodonetsk, ordered a mixed tactical unit to mine the tanks containing nitrate and nitric acid in the Azot factory," it said.</p>.<p>Russia's army said this group still in the city included "survivors" of the 79th Air Assault Brigade and members of the Ukrainian Territorial Defence Forces.</p>.<p>It claimed the Ukrainian army sought to contaminate the area and "delay" the Russian military operation.</p>
<p>Russia's army said Saturday that some Ukrainian military units were withdrawing from the key city of Severodonetsk in eastern Ukraine.</p>.<p>"Some units of the Ukrainian army, having suffered critical losses during fighting for Severodonetsk, are pulling out towards Lysychansk," Severodonetsk's twin city, which sits just across a river, the defence ministry said in a statement.</p>.<p>It added however that some Ukrainian fighters remained in the city.</p>.<p>"The Ukrainian authorities, having realised that it was impossible to resist further and to hold on to the industrial zone of Severodonetsk, ordered a mixed tactical unit to mine the tanks containing nitrate and nitric acid in the Azot factory," it said.</p>.<p>Russia's army said this group still in the city included "survivors" of the 79th Air Assault Brigade and members of the Ukrainian Territorial Defence Forces.</p>.<p>It claimed the Ukrainian army sought to contaminate the area and "delay" the Russian military operation.</p>