Ukrainian forces have kept pushing north in the Kharkiv region and advancing to its south and east, Ukraine's army chief says, a day after their rapid gains made Russia abandon its main bastion in the area.
President Volodymyr Zelenskiy hailed Ukraine's advance in the northeast Kharkiv province as a potential breakthrough in the six-month-old war, saying this winter could bring more rapid gains of territory if Kyiv can get more powerful weapons.
"In the Kharkiv direction, we began to advance not only to the south and east, but also to the north. There are 50 km to go to the state border (with Russia)," Ukraine's chief commander General Valeriy Zaluzhnyi said on Telegram on Sunday.
He said the country's armed forces have regained control of more than 3,000 square km since the beginning of this month.
In Moscow, Russia's defence ministry said on Sunday that Russian forces were hitting Ukrainian army positions in the Kharkiv region with precision strikes delivered by airborne troops, missiles and artillery.
The retreat from the city of Izium marked Russian forces' worst defeat since they were pushed back from the capital Kyiv in March, as thousands of Russian soldiers left behind ammunition and equipment as they fled.
The gains are important politically for Zelenskiy as he seeks to keep Europe united behind Ukraine - supplying weapons and money - even as an energy crisis looms this winter following cuts in Russian gas supplies to European customers.
"I believe that this winter is a turning point, and it can lead to the rapid de-occupation of Ukraine," Zelenskiy said in comments to a political forum published on his website late on Saturday. "We see how they (occupiers) are fleeing in some directions. If we were a little stronger with weapons, we would de-occupy faster."
Ukrainian officials stopped short of confirming they had recaptured Izium, but Zelenskiy's chief of staff Andriy Yermak posted a photo of troops on its outskirts and tweeted an emoji of grapes. The city's name means "raisin".
Kyiv-based military analyst Oleh Zhdanov said the gains could pave the way for a further push into Luhansk region, whose capture Russia claimed at the beginning of July.
As the war entered its 200th day, Ukraine reported more Russian missile and air strikes overnight and regional officials reported heavy Russian shelling in the east and south.
While fighting raged, conditions at Europe's biggest nuclear power plant continued to cause global concern. Russia and Ukraine accuse each other of shelling around the Zaporizhzhia plant and thereby risking a catastrophic release of radiation.
But on Sunday the International Atomic Energy Agency said a backup power line to the Russian-held plant had been restored, providing it with the external electricity it needs to cool its reactors and defend against the risk of a meltdown.
State agency Energoatom meanwhile said it halted operations at the plant as a safety step, as the restored line to the grid allowed the plant to be powered by Ukraine's energy system.
Kyiv on Wednesday had urged residents of Russian-occupied areas around the plant to evacuate for their own safety.
The continent's energy crisis this winter threatens to erode European unity on Ukraine, and Kyiv badly needs to show that not only it can hold out against Moscow's assault but also sway the war's momentum in its favour.