Dozens of civilians trapped for weeks inside a steel plant in the devastated Ukrainian city of Mariupol were expected to reach Zaporizhzhia on Monday, according to Ukrainian President Volodymyr Zelenskyy.

In a statement posted to Twitter on Sunday, Zelenskyy said a first group of about 100 people were already en route to the Ukrainian government-controlled city, about 140 miles northwest of Mariupol.

"Tomorrow we'll meet them in Zaporizhzhia," Zelenskyy tweeted. "Grateful to our team!"

Many more civilians remain trapped at the sprawling Azovstal Iron and Steel Works plant in Mariupol -- the last holdout of Ukrainian resistance to Russia's bombardment of the strategic southeastern port city -- which Russian forces resumed shelling overnight.

"Today, for the first time in all the days of the war, this vitally needed green corridor has started working," Zelenskyy said Sunday in his nightly address.

A pair of "powerful explosions" were heard early Monday in the western Russian city of Belgorod, about 15 miles from the border with Ukraine, according to the regional governor.

"I woke up to the sound of two powerful explosions half an hour ago. According to the anti-crisis center, there were no reports of casualties or damage. Footage showing flashes in the sky has emerged on social media," Belgorod Oblast Gob. Vyacheslav Gladkov said in a statement posted on Telegram.

The blasts followed a series of other explosions and fires at industrial and military facilities across Russia in recent weeks. On Sunday, the governor of Russia's western Kursk Oblast, which also shares a border with Ukraine, said a railway bridge used to transfer Russian troops to Ukraine had partially collapsed. In a video posted on Telegram, Kurk Oblast Gov. Roman Starovoit blamed the incident on sabotage.

-ABC News' Edward Szekeres, Max Uzol, Irene Hnatiuk and Fidel Pavlenko

Over a quarter of Russian military units committed to fight in Ukraine have been likely rendered "combat ineffective," the U.K. Ministry of Defense said Monday in an intelligence update.

"At the start of the conflict, Russia committed over 120 battalion tactical groups, approximately 65% of its entire ground combat strength," the ministry said. "It is likely that more than a quarter of these units have now been rendered combat ineffective."

Meanwhile, some of Russia's most elite units, including the Russian Airborne Forces or VDV, "have suffered the highest levels of attrition," according to the ministry.

"It will probably take years for Russia to reconstitute these forces," the ministry added.

On Sunday, Ukrainian presidential adviser Oleksiy Arestovych said at least 30 senior Russian military officers have been eliminated in the previous five days.

-ABC News' Edward Szekeres, Max Uzol, Irene Hnatiuk and Fidel Pavlenko

Israel on Monday lashed out at Russia over "unforgivable and scandalous" remarks made by its top diplomat about Nazism and antisemitism, including claims that Adolf Hitler was Jewish.

During an interview Sunday with an Italian television channel, Russian Foreign Minister Sergey Lavrov was asked about Moscow's assertion that it invaded neighboring Ukraine to "denazify" the country. Lavrov said the fact that Ukrainian President Volodymyr Zelenskyy is Jewish does not negate the Nazi elements in his country, drawing a parallel with Hitler, the chancellor of Nazi Germany.

"So when they say: 'How can Nazification exist if we're Jewish?' In my opinion, Hitler also had Jewish origins, so it doesn't mean absolutely anything. For some time we have heard from the Jewish people that the biggest antisemites were Jewish," Lavrov said, speaking to the station in Russian, dubbed over by an Italian translation.

Russia does not insist on Zelenskyy's surrender, Lavrov said, but wants the Ukrainian president to order "neo-Nazi battalions to halt resistance, lay down their arms and let civilian hostages go." Lavrov alleged that Moscow only seeks to guarantee the security of pro-Russia Ukrainians in the eastern regions.

Lavrov's comments came at a time when Israel, which was created as a refuge for Jews in the wake of the Holocaust, has sought to remain neutral amid Russia's war in Ukraine. However, Israeli Foreign Minister Yair Lapid condemned the statement made by his Russian counterpart as "unforgivable and scandalous and a horrible historical error."

"The Jews did not murder themselves in the Holocaust," Lapid, the son of a Holocaust survivor, said Monday. "The lowest level of racism against Jews is to blame Jews themselves for antisemitism."

Ukraine also denounced Lavrov's statement, with Ukrainian Foreign Minister Dmytro Kuleba saying it exposes "the deeply-rooted antisemitism of the Russian elites."

-ABC News' Edward Szekeres, Max Uzol, Irene Hnatiuk and Fidel Pavlenko

White House national security advisor Jake Sullivan hinted Thursday of more sanctions coming against Russia in the "next week or two" aimed at targeting ways Moscow is evading sanctions already imposed.

“Where our focus will be over the course of the coming days is on evasion,” Sullivan said Thursday at the Economic Club of Washington. “As Russia tries to adjust to the fact that it’s under this massive economic pressure, what steps do they take to try to evade our sanctions and how do we crack down on that? And I think we'll have some announcements in the next week or two that identify targets that are trying to facilitate that evasion both inside Russia and beyond."

When Sullivan was asked whether sanctions will automatically be lifted if a negotiated peace deal between Russia and Ukraine is worked out, he appeared cautious with his words, saying, “a lot of that depends on what the shape and scope” of the agreement is.

“A lot of it depends on what the Ukrainians, in consultation with us and the Europeans come to agree to," Sullivan said. "You know, we're not going to do a deal over the head of the Ukrainians where we give a bunch of sanctions relief to Russia. But if some measure of sanctions relief were built in to some credible diplomatic solution led by the Ukrainians, that's something that we would happily discuss."

But Sullivan said Russian oligarchs shouldn't expect to ever get back their yachts and other assets seized under sanctions that have been imposed, saying the ultimate goal is "not to give them back” once the war is over.

“The president is actively looking at how we can deal with the fact that as we seize these assets, our goal is not to give them back. Our goal is to put them to a better use than that," Sullivan said. "But I'll be careful in what I say today because there's an ongoing kind of policy process around how we end up dealing with that question. But, rest assured, that the goal is not just to sit on them for a while."

-ABC News' Justin Gomez