The General Staff of the Ukrainian armed forces said in an evening statement that the Russian attacks near Izyum were unsuccessful and that a counter-attack had recaptured Maryinka, forcing the Russians to retreat.

A major Russian assault was also reported at Hulyaipole, in the Zaporizhzhya region, where the front line has been static for more than a month. It was not immediately clear if that attack had made progress.

Pro-Russian figures said that they had launched a final infantry assault on the Azovstal steel factory in Mariupol, where an unknown number of Ukrainian soldiers are making their last stand. A large number of civilians are also believed to be sheltering there.

Denis Pushilin, the head of the self-proclaimed Donetsk People’s Republic, said that the goal was to capture the factory as soon as possible. Ramzan Kadyrov, the Kremlin-appointed head of Chechnya, said that he expected the last defenders to be rooted out “in hours”.

Ukrainian forces were also preparing to resist a Russian attempt to go as far as the Dnieper River.

Russia’s initial, largely unsuccessful attacks in February appeared to envisage a major encirclement converging on Dnipro, the industrial city that controls access to the east and is Ukraine’s most important logistical hub in the area.