President Joe Biden authorized $200 million in new military assistance to Ukraine, to come from existing U.S. weapons stocks, the White House said Saturday.

Biden authorized "the drawdown of up to an aggregate value of $200 million in defense articles and services of the Department of Defense, and military education and training, to provide assistance to Ukraine and to make the determinations required under such section to direct such a drawdown," the White House said in a press release.

-ABC News' Justin Gomez

Russian President Vladimir Putin spoke on the phone with French President Emmanuel Macron and Federal Chancellor of Germany Olaf Scholz, about the humanitarian situation in Ukraine, the Kremlin's press service reported on Saturday.

The Kremlin claimed "numerous facts of gross violations of international humanitarian law by Ukrainian security forces were cited - extrajudicial killings of dissenters, taking hostages and using civilians as human shields, placing heavy weapons in residential areas, near hospitals, schools, kindergartens."

The Kremlin also claimed, "nationalist battalions systematically disrupt rescue operations, intimidate civilians during evacuation attempts."

Putin "urged" Macron and Scholz to "influence the Kiev authorities so that such criminal actions would be stopped," according to a statement from the Kremlin.

The leaders spoke about the series of talks between Russian and Ukrainian representatives in recent days. "It was agreed to continue contacts on Ukrainian issues," the Kremlin said.

Ukrainian President Volodymyr Zelenskyy Saturday demanded the release of Melitopol Mayor Ivan Fedorov, who Ukrainian officials allege was kidnapped by Russian forces.

"The city community is demanding his release. I am grateful to every Melitopol resident for this resistance," Zelenskyy said in a message posted on Facebook.

The organizer of Ukrainian rallies in Melitopol, Olga Gaisumova was also captured and the city's aid headquarters in the Shevchenko recreation center was seized by Russian soldiers, who cordoned off the building, local blogger and activist, Tatiana Kumok, told ABC News in an interview.

The occupiers told the civil defense in Melitopol that they are prohibited from going in the streets during the curfew, according to Kumok.

Zelenskyy claimed the Ukrainians have had tremendous success, dealing "biggest blow to the Russian army in decades."

"We have had extraordinary success. How the entire Ukrainian people resisted these invaders has already gone down in history. But we have no right to reduce the intensity of defense, no matter how difficult it may be for us. We have no right to reduce the energy of our resistance," Zelenskyy said.

In his latest address, Ukrainian President Volodymyr Zelenskyy demanded the release of a mayor reportedly kidnapped Friday by Russian forces.

"Today in Melitopol, the invaders captured mayor of the city, Ivan Fedorov -- a mayor who courageously defends Ukraine and the people of his community," Zelenskyy said. "Obviously, this is a sign of the weakness of the invaders."

He called the alleged kidnapping a "crime against democracy" and said Russia's actions "will be equated with the actions of ISIS terrorists."

"Ukraine demands the immediate release of the mayor of Melitopol and guarantees of full security to all heads of communities across the country," he said, adding that he planned to raise this in talks with "international mediators who communicate with Moscow."

The southern Ukrainian city of Melitopol has been under Russian occupation since the first days of the invasion, though Fedorov had insisted it remained part of Ukraine.

Zelenskyy adviser Kirill Timoshenko posted a CCTV video Friday allegedly showing Fedorov being led out of the building by a large group of armed Russian soldiers.