Ukrainian President Volodymyr Zelensky has publicly acknowledged for the first time that his troops are active in Russia's Belgorod region, which borders Ukraine. "We continue to carry out active operations in the border areas on enemy territory, and that is absolutely just - war must return to where it came from," he said on Monday.

Russia has been trying since August last year to eject Ukrainian forces from Kursk after Kyiv's troops mounted a surprise incursion that embarrassed President Vladimir Putin and which Ukrainian President Volodymyr Zelenskiy hoped would give him a bargaining chip in any future talks.