KYIV, Ukraine (AP) — Voting began in Russian-held regions of Ukraine on referendums to become part of Russia, Moscow-backed officials there said Friday as Ukrainian and United Nations officials reported evidence of war crimes during the nearly seven-month war in the country.

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 counteroffensive this month, reported 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.

Gov. 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 U.N. Human Rights Council also presented evidence 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 didn't 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 mobilization of reservists, which could add about 300,000 Russian troops to the fight. The balloting will continue for five days through Tuesday.

The referendums ask residents if they want their regions to be part of Russia, is 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 underway in the occupied regions, Russian social media sites were full of dramatic scenes of tearful families bidding farewell to men departing from military mobilization centers. 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 mobilization.

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."

Vyacheslav Volodin, speaker of Russia's lower house of parliament, the State Duma, addressed the occupied regions 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 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.

Heavy fighting also continued in the Donetsk region where Russian attacks targeted Toretsk and Sloviansk as well as several smaller towns. Russian shelling in Nikopol and Marhanets on the western bank of the Dnieper River resulted in the deaths of two people and the wounding of nine in Marhanets.

Vitaliy Kim, governor of the Mykolaiv region in southern Ukraine that borders the Kherson region, said explosions rang out in the city of Mykolaiv in the early hours of Friday.

Pro-Russia officials in the Zaporizhzhia region reported a loud blast in the early hours of Friday in the center of Melitopol, a city that Moscow captured early on in the war. Official Vladimir Rogov didn't offer any details as to what caused the explosion and whether there was damage and casualties.

Moscow-backed authorities in the Donetsk region also accused Ukrainian forces of shelling the city of Donetsk, the region's capital, and the nearby city of Yasynuvata.

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