Russian President Vladimir Putin announced on Wednesday that Russia would impose martial law in the four regions in Ukraine Moscow last month claimed as its own territory.

Speaking to his National Security Council, Putin announced the declaration of martial law in Kherson, Zaporizhzhia, Luhansk and Donetsk.

"We are working on solving very complex, large-scale tasks to ensure a reliable future for Russia, the future of our people," he said.

Putin didn't immediately spell out the steps that would be taken under martial law, but said his order would be effective starting Thursday.

Draft legislation indicates it may involve restrictions on travel and public gatherings, tighter censorship and broader authority for law enforcement agencies all aimed at firming the Moscow's grip on four Ukrainian regions Russia illegally annexed.

Putin also ordered the establishment of a Coordination Committe aimed at fulfilling the objectives of his so-called special military operation, the Kremlin's euphemism for the war in Ukraine.

Ukrainian presidential adviser, Mykhailo Podolyak, dismissed Putin's declaration.

"'Martial law' implementation on the occupied territories by Russia should be considered only as a pseudo-legalization of looting of Ukrainians’ property by another 'regrouping'," the adviser, Mykhailo Podolyak, wrote on Twitter.

"This does not change anything for Ukraine: we continue the liberation and deoccupation of our territories," he added.

City of Kherson under pressure, says Russia

The Russian military currently controls only parts of the annexed areas and Putin's move comes as officials in occupied Kherson told civilians to leave some areas as soon as possible in anticipation of an imminent Ukrainian attack.

Russian forces are losing ground in the illegally annexed territories with an Ukraine's counteroffensive bearing down on Kherson.

Russian forces started the mass evacuations of civilians Wednesday from Kherson, one of the first major cities they seized in the invasion of Ukraine.

"The entire administration is already moving today," Moscow-installed regional head Vladimir Saldo, said on Russian state television. 

"No one is going to hand over Kherson. But it is not ideal for residents to be in the city where hostilities will take place," Saldo added.

Andriy Yermak, the head of the Ukrainian president's office, said Russia was putting on a propaganda show in Kherson.

"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," Yermak wrote on the Telegram messaging app.

lo/wmr (AP, Reuters)