Russia said on Tuesday that its troops had made major new gains in its western region of Kursk, accelerating their push to drive out Ukrainian forces who have been clinging on to a slice of Russian territory since last August.

Russian troops hunched, dirt on their faces, as they crept through an empty gas pipeline under Ukrainian defence lines. One Ukrainian political and military commentator said Russian troops had already briefly captured a building on the outskirts of Sudzha by attacking via the pipeline before being beaten back.