More than two-and-a-half years since Russia's invasion, the war in Ukraine is at a critical juncture, with Moscow regularly pounding Ukrainian infrastructure as its troops try to complete the capture of the whole of Ukraine's eastern Donbas region.
The United States says Iran has supplied hundreds of ballistic missiles to Russia in a major escalation.
Moscow has warned the West against green-lighting deep strikes into Russian territory with Western weapons, warning it would respond.
Russian forces have been gaining ground in parts of east Ukraine including Pokrovsk, whose capture could enable Moscow to open up new lines of attack and complicate Ukrainian logistics in the east.
Russia is regularly pounding infrastructure as its troops press on in Ukraine's east. (AP PHOTO)
Donetsk's regional governor said a filtering station had stopped working because of heavy fighting, severing the water supply to Pokrovsk.
He said it would be impossible to fix soon and renewed calls to civilians to flee the town.
"The situation is difficult and it won't get better soon. So I again call on you to evacuate!" the official, Vadym Filashkin, wrote on the Telegram messaging app on Thursday.
The town, which straddles several important roads that pass through the Donetsk region and has a rail line, has also lost supply of electricity and gas used for cooking and heating, local authorities said.
Russian momentum has slowed in the areas nearest Pokrovsk, but Moscow's forces have pressed south from that line of attack, closing in on the nearby town of Ukrainsk, open-source intelligence reports by Ukraine's Deep State analysts indicate.
Ukraine's military said their forces on the nearby Kurakhiv front, which includes Ukrainsk, were continuing to hold back Moscow's troops.
Russia tried to break through Kyiv's lines in the area 23 times in the past day, it said.
Some Russian military bloggers said Moscow's forces had almost taken control of Ukrainsk, which had a pre-war population of more than 10,000.
There was no immediate update from Russia on its advance in the area.
After months on the back foot in the east, Kyiv's forces launched a surprise incursion into Russia's Kursk region in August, making rapid progress in an attempt to seize the initiative in the war and divert Russian forces from the east.
Ukraine has tried to take the fight back to Russia by launching hundreds of drones at its territory. (AP PHOTO)
Russia has kept up its offensive pressure in the east, though, and a Russian commander said on Wednesday his forces had taken back control of about 10 settlements in Kursk region.
Reuters could not independently verify the battlefield reports.
The city of Konotop, a rail hub in Sumy region that Kyiv used as a staging ground for its cross-border incursion, reported heavy damage from an overnight Russian drone attack.
Local officials said at least 14 people had been hurt in an attack that "significantly" damaged energy infrastructure and cut electricity to the settlement.
Regional officials said there were 10 explosions during the attack and Mayor Artem Semenikhin said the power system was in critical condition.
"At the moment, energy workers are doing everything they can to provide electricity to the hospital and the water supply system," he said.
The strike on Konotop was part of a broader Russian attack using 64 drones, the air force said.
It shot down 44 of them over nine regions, it said.
Such attacks have become almost nightly occurrences since Russia invaded Ukraine in February 2022.
Though Ukraine is heavily outgunned and lacks a large arsenal of long-range missiles, it has tried to take the fight back to Russia by launching hundreds of drones at it.
