Moscow’s forces are three miles from Dnipropetrovsk, a province they have never invaded. If they cross in, the advance would be a morale blow to Ukraine and complicate any territorial negotiations.

Russian forces have taken back more than 800 square km (309 square miles) of territory from Ukraine in the Kursk region of western Russia, or about 64% of the total taken by Ukraine since an incursion began last year,

The US signaled that sanctions relief for Russia could be on the table in talks over the war in Ukraine as President Donald Trump rushes toward a deal to end the three-year conflict.