Poland's president is scheduled to address Ukraine's parliament Sunday.
Andrzej Duda will be the first foreign head of state to speak to Ukraine's Verkhovna Rada since Russia's invasion of Ukraine. Poland has accepted more than 2 million Ukraine refugees.
There will be no cease-fire or concessions to Russia, Ukraine's lead negotiator said Saturday as Russia upped its assault on Luhansk, one of the two provinces that make up the Donbas in eastern Ukraine.
'The war will not stop (after concessions). It will just be put on pause for some time,' Mykhailo Podolyak, who is also an adviser to Ukrainian President Volodymyr Zelenskyy, said, explaining Ukraine's position in light of recent calls for a cease-fire from U.S. Defense Secretary Lloyd Austin and Italian Prime Minister Mario Draghi. 'They'll start a new offensive, even more bloody and large-scale,' Podolyak added.
Pro-Russian separatists have fought Ukraine for control of the Luhansk and Donetsk provinces - which together make up the Donbas - since 2014, when Russia seized the Crimean Peninsula.
Ukrainian forces in the two provinces said via Facebook that at least seven people had been killed in Donetsk in the previous 24 hours when Russians, using aircraft, artillery, tanks, rockets, mortars and missiles, pummeled civilian structures and residential areas, Reuters reported.
The Ukrainians said they had turned back nine attacks, destroying five tanks and 10 armored vehicles, according to the Facebook post.
'The situation in Donbas is extremely difficult,' Zelenskyy said Saturday in his nightly address. He said Ukrainian forces were holding off the Russian army as it was trying to attack the cities of Sloviansk and Sievierodonetsk.
In another development Saturday, Russia published a list of nearly 1,000 Americans who are permanently banned from entry into Russia because of their support for Ukraine. U.S. President Joe Biden and Vice President Kamala Harris are among those on the list that also includes members of the president's Cabinet.
On Friday night Zelenskyy said that victory against Russia will ultimately come through a diplomatic settlement.
A wedding photograph lies among rubble from a Russian strike earlier in the war in Kramatorsk, eastern Ukraine, May 21, 2022.
"The victory will be difficult, it will be bloody and in battle, but its end will be in diplomacy. I am very convinced of this," Zelenskyy said in a Ukrainian television interview late Friday. "There are things that we can't bring to an end without sitting at the negotiation table."
The Ukrainian leader also said his country is attempting to recover fighters who surrendered to Russian forces after weeks of fighting at the Azovstal steel plant in the southern port city of Mariupol.
"Everything will depend on (the responsibilities) the U.N., the Red Cross and the Russian Federation took on themselves, that they (the fighters) all will be in safety, waiting for one or the other exchange format," he said. He said Ukraine's intelligence service is making preparations "for a dialogue and an exchange.'
Russia launched a full-scale invasion of Ukraine nearly three months ago, on Feb. 24.
Concern for the treatment of those fighters increased Saturday when Denis Pushilin, the pro-Kremlin head of an area of eastern Ukraine controlled by Moscow-backed separatists, said they would face tribunals.
Pushilin said there were 2,439 people in custody, including some foreign nationals among the fighters.
Deputy Prime Minister Iryna Vereshchuk said Saturday that Ukraine would fight for the return of every soldier.
There was no immediate confirmation from Ukraine that Mariupol was fully under Russian control.
The port city is the scene of the war's bloodiest siege, with Russian forces bombarding it for nearly three months. Much of Mariupol has been reduced to rubble, and more than 20,000 civilians are feared dead.
But its capture adds to Moscow's goal of a land route from Russia to the Crimea and perhaps beyond.
Russia destroyed a Ukrainian special operations base near Odesa, Ukraine's main Black Sea port on Saturday, as well as a significant cache of Western-supplied weapons in northern Ukraine's Zhytomyr region, The Associated Press reported, quoting Russian Defense Ministry spokesperson Igor Konashenkov. There was no confirmation from the Ukrainian side.
Destroyed trams stand in a depot in Mariupol, in territory under the government of the Donetsk People's Republic, eastern Ukraine, May 21, 2022.
The end of the fighting in Mariupol not only gives Russian President Vladimir Putin a victory, but it allows him to shift fighters east to the Donbas.
Among the developments there:
The only functioning hospital in Sievierodonetsk, the main city under Ukrainian control in the Luhansk region, has three doctors left and enough supplies for 10 days, Gov. Serhii Haidai said.
Haidai also said Russian troops destroyed a bridge on the Siverskiy Donets River between Sievierodonetsk and Lysychansk. There was fighting on the outskirts of Sievierodonetsk from morning through the night, Haidai said on the Telegram messaging app.
A monastery in the village of Bohorodichne in the Donetsk region was evacuated after it was hit by a Russian airstrike, the regional police said Saturday, the AP reported.
About 100 monks, nuns and children had been sheltering in the basement of the church and no one was hurt, the police said in a Facebook post, which included a video of the damage to the monastery as well as nuns, monks and children boarding vans on Friday for the evacuation.
Zelenskyy on Saturday emphasized that the Donbas remains part of Ukraine and his forces were fighting to liberate it.
Some information for this story came from The Associated Press and Reuters.