Russian President Vladimir Putin has announced martial law in the four regions that Moscow recently annexed from Ukraine.
He also granted emergency powers to the heads of other Russian regions on Wednesday afternoon.
Putin didn't immediately spell out the measures that would be taken under the martial law, but Russian legislation suggests it may involve restrictions on travel and public gatherings and tighter censorship, as well as giving broader powers to law enforcement agencies.
Putin didn't spell out the extra powers to be given to the heads of Russian regions under his decree, in moves that were the latest sign that the fighting in Ukraine isn't going his way.
The news came as Russia began evacuating Kherson - one of four regions Moscow illegally annexed last month - as officials say they are preparing to defend the captured southern city from an imminent Ukrainian attack and urged civilians to flee.
The head of the office of Ukrainian president Volodymyr Zelensky has dismissed the evacuation, however, as a “propaganda show” by Russia.
On Wednesday, residents received urgent text messages urging them to leave the southern city - which was one of the first seized by Russian forces when the country invaded Ukraine in February - Russia's state news agency RIA Novosti reports.
Photos appeared to show Kherson residents gathered on the banks of the Dnipro river, preparing to cross it as they evacuate the area on Wednesday morning.
#Kherson evacuation is ongoing. Doesn't seem very busy, is it? 😉 pic.twitter.com/O0PtScScAg
— NOËL 🇪🇺 🇺🇦 (@NOELreports) October 19, 2022
Moscow-backed authorities have said evacuations from occupied territories are voluntary. The forced movement of residents would be a war crime under the United Nations definition.
Andriy Yermak, head of President Zelensky’s office, has dismissed the evacuation plan and accused Russia of organising a "propaganda show”.
Mr Yermak also accused Russia of trying to scare Kherson residents with what he described as fake newsletters about Ukrainian shelling of the city in southern Ukraine.
"The Russians are trying to scare the people of Kherson with fake newsletters about the shelling of the city by our army, and also arrange a propaganda show with evacuation," he wrote on the Telegram messaging app. "Propaganda will not work."
Kirill Stremousov, a Russian regional official, said that “the battle for Kherson will begin in the very near future” and that civilians should be ready to be evacuated.
“Please take my words seriously - I’m talking about evacuating as quickly as possible,” he said on the Telegram messaging service.
“The civilian population is advised to leave the area of the forthcoming fierce hostilities, if possible, so as not to expose themselves to unnecessary risk,”
The Russian installed governor of Kherson, Vladimir Saldo, added that between 50,000 and 60,000 people would be evacuated to Russia and to the left bank of the Dnipro over the next six days.
Kherson, which was taken by Russia in the early weeks of the war, is the only regional capital in Ukraine to have fallen to Moscow’s forces since the conflict began and any defeat there would be another major blow to Vladimir Putin in the wake of other recent military reverses.
It is one of four partly or fully-occupied regions that Russia illegally annexed last month, in an effort - widely condemned and rejected by Western nations - to cement its land-grabs.
Proving incapable of holding all the territory it seized and struggling with manpower and equipment losses, Russia has stepped up bombardments from the air.
But General Sergei Surovikin, the commander of Russia’s forces in Ukraine, also admitted that Moscow’s troops are facing a “difficult” and “tense” situation.
“The enemy continually attempts to attack the positions of Russian troops,” he said. “As a whole the situation in the special military operation zone can be described as tense.”
He also admitted that Ukrainian forces were attacking elsewhere in other parts of the country, including on the Mykolaiv-Krivyi Rih front in the south and around Kupiansk and Lyman in the east.
News of the evacuation come as Russian missile strikes and shelling of energy utilities left more Ukrainian villages, towns and parts of two cities without power on Wednesday, authorities said, tightening an energy squeeze that threatens misery for millions in winter.
A nearly fortnight-long barrage of Russian attacks with missiles, self-destructing explosive drones and other weaponry on Ukraine’s critical infrastructure comes as Russian forces are being forced back on the ground.
The scorched-earth campaign targeting Ukrainian power plants and other key infrastructure contrasts with Kremlin tactics in the invasion's opening stage, when Russian commanders had seemingly sought to spare some utilities they perhaps thought they might later need, had they not been beaten back.
Ukrainian President Volodymyr Zelensky tweeted Tuesday that nearly a third of Ukraine's power stations have been destroyed since October 10, causing "massive blackouts" nationwide.
Later on Tuesday, in his nightly video address, Zelensky urged Ukrainians to make "a very conscious" effort to save power, speaking before another night where substations and other infrastructure were pounded.
Zelensky said switching off appliances and doing other things to save power during hours of peak consumption help "the entire country."