The Kremlin-orchestrated referendums, which have been widely denounced by Ukraine and the West as shams without any legal force, are seen as a step toward annexing the territories by Russia.
The votes are being held in the Luhansk, Kherson and partly Russian-controlled Zaporizhzhia and Donetsk regions.
The governor of the Kharkiv region, which was mostly held by Russian forces before a Ukrainian counter-offensive this month, reported on Friday that 436 bodies have been exhumed from a mass burial site in the eastern city of Izium, 30 of them with visible signs of torture.
Governor Oleh Synyehubov and the region’s police chief, Volodymyr Tymoshko, told reporters in Izium that three more grave sites have been located in areas retaken by Ukrainian forces.
A team of experts commissioned by the UN Human Rights Council also presented evidence on Friday of crimes including beatings, electric shocks and forced nudity in Russian detention facilities, as well as executions in the regions of Kyiv, Chernihiv, Kharkiv and Sumy.
But the commission’s chairman did not specify who or which side in the war committed most of the alleged crimes.
The referendum votes follow Russian President Vladimir Putin’s order of a partial mobilisation of reservists, which could add about 300,000 Russian troops to the fight. The balloting will continue for five days through to Tuesday.
The referendums, which ask residents if they want their regions to be part of Russia, are certain to go Moscow’s way. That would give Russia the pretext to claim that attempts by Ukrainian forces to regain control are attacks on Russia itself, dramatically escalating the war.
As the votes were getting under way in the occupied regions, Russian social media sites were full of dramatic scenes of tearful families bidding farewell to men departing from military mobilisation centres.
In cities across the vast country, men hugged their weeping family members before departing as part of the draft. Russian anti-war activists, in the meantime, planned more protests against the mobilisation.
Election officials will be bringing ballots to people’s homes and setting up makeshift polling stations near residential buildings during the first four days of the referendums, according to Russian-installed officials in the occupied regions, who cited safety reasons. Tuesday will be the only day when the voters will be invited to come to regular polls.
Polls also opened in Russia, where refugees from the occupied regions can cast their votes.
Denis Pushilin, separatist leader of Moscow-backed authorities in the Donetsk region, called the referendum on Friday “a historical milestone”.
Latest Defence Intelligence update on the situation in Ukraine – 23 September 2022
Find out more about the UK government’s response: https://t.co/Bot9jAVNWg
— Ministry of Defence 🇬🇧 (@DefenceHQ) September 23, 2022
Vyacheslav Volodin, speaker of Russia’s lower house of parliament, the State Duma, addressed the occupied regions on Friday in an online statement, saying: “If you decide to become part of the Russian Federation — we will support you.”
Valentina Matviyenko, chair of Russia’s upper parliament house, said that residents of the occupied regions were voting for “life or death” at the referendums.
Ukrainian President Volodymyr Zelenskyy only briefly mentioned the “sham referenda” in his nightly address in which he switched from speaking in Ukrainian to Russian to directly tell Russian citizens they are being “thrown to their deaths”.
“You are already accomplices in all these crimes, murders and torture of Ukrainians,” he said. “Because you were silent. Because you are silent. And now it’s time for you to choose.
“For men in Russia, this is a choice to die or live, to become a cripple or to preserve health. For women in Russia, the choice is to lose their husbands, sons, grandchildren forever, or still try to protect them from death, from war, from one person.”
The voting takes place against the backdrop of incessant fighting in Ukraine, with Russian and Ukrainian forces exchanging fire as both sides refuse to concede ground.
Ukraine’s presidential office said on Friday at least 10 civilians were killed and 39 others were wounded by Russian shelling in nine Ukrainian regions over the last 24 hours.
It said that fighting has continued in the Russia-held southern Kherson despite the voting, while Ukrainian forces troops meted out 280 attacks on Russian command posts, munitions depots and weapons in the region.