Kyiv residents have been urged to cut down on electricity use in the evenings, after a Russian missile strike disabled a power installation near the capital.
Officials said power had been restored across Ukraine earlier after Russian missiles hit energy infrastructure.
But Ukraine’s state energy operator Ukrenergo has still called for the reduction between 17:00 and 23:00 (15:00 – 21:00 GMT), warning of possible power cuts.
The request was not confined to Kyiv.
The deputy head of Ukraine’s presidential administration, Kyrylo Tymoshenko, said the populations of Zhytomyr, Cherkasy and Chernihiv should also save electricity.
“If this advice is ignored, we will have difficulties and it will be necessary to take out the candles,” he warned on Telegram.
Ukrenergo has urged residents to save electricity in the evening by not using energy-guzzling appliances, switching off unnecessary lighting and doing their washing at night.
However, the BBC’s Paul Adams reports that Kyiv streets are already darker than usual at night, but “life very much goes on”.
The energy warning comes as more heavy fighting is reported north of Russian-held Kherson.
Kirill Stremousov, a Russian-appointed leader in the southern region, said Ukrainian shelling was coming from the Dudchany area, on the west bank of the Dnieper river (called Dnipro by Ukrainians).
Advancing Ukrainian forces have repeatedly bombarded bridges over the river, aiming to cut off Russian troops in Kherson city.
Russian-installed officials in the city have urged Moscow to help transfer Kherson families to Russian cities as Ukrainian shelling intensifies.
President Vladimir Putin has declared Kherson and three other Ukrainian regions to be part of Russia – a move condemned internationally, after hastily-organised so-called referendums in the regions.
Meanwhile, Ukrainian prosecutors have accused Russian soldiers of shooting and killing the chief conductor of the Kherson Music and Drama Theatre, Yuri Kerpatenko, in his home. It is widely reported on Ukrainian media, but there are few details. He is said to have refused to co-operate with the occupation authorities.
Russian oil depot fire
For two days running the governor of Belgorod, a Russian city 40km (25 miles) north of Ukraine, has reported Ukrainian cross-border shelling. One shell caused a major fire at an oil depot near the city on Saturday, Vyacheslav Gladkov said, adding later that firefighters had extinguished it.
Ukrainian shelling set fire to an electricity substation in Belgorod on Friday, he reported on Telegram. In that case too the fire was contained. Kyiv has not commented on the Russian claims, but there have been explosions in the Belgorod region previously, which Russia blamed on Ukrainian shelling.
On Friday President Putin said he saw no need for further massive missile strikes against Ukraine “for now”, on the scale of last Monday’s, which hit Kyiv and other cities, killing at least 20 civilians. Mr Putin said those strikes were retaliation for the attack that damaged Russia’s huge Kerch bridge – a key strategic link to annexed Crimea.
Another focus of fighting in the south is Zaporizhzhia – Ukrainian officials in the city say it was hit by more Russian missiles and Iranian-made Shahed “kamikaze” drones overnight. There was damage to energy facilities and industrial infrastructure there.
The Zaporizhzhia nuclear power plant – Europe’s largest – lies just south of the city, under Russian control, and repeated shelling in the area has raised fears of a nuclear disaster.
The US has announced $725m (£649m) of further military aid for Ukraine, including ammunition for Himars rocket systems, artillery rounds, anti-tank weapons and Humvee armoured vehicles. The US has provided more than $17bn of military aid since Russia’s 24 February invasion – by far the largest contribution among Ukraine’s Western allies.
On Ukraine’s northern border, Belarus says a new Russian military contingent has arrived – part of what it describes as a regional border protection force. Belarus has hosted Russian forces involved in the war in Ukraine, including those who launched an abortive assault on Kyiv. But so far it has not sent its own troops across the border.