Media reports say hundreds of Ukrainian fighters defending Mariupol’s Azovstal steelworks surrendered on Tuesday, May 17.  

Western media reports say Russian forces pummeled Mariupol, a major port on the Sea of Azov between Russia and Crimea, with artillery for weeks.  After the urban warfare that followed, the city is reportedly a wasteland.

Meanwhile, Russia's defense ministry said 265 fighters had surrendered, including 51 who were seriously wounded and would be treated at Novoazovsk in the Donetsk region.

Five buses reportedly took wounded fighters there early on Tuesday, and in the evening.

Reuters says seven more buses, escorted by armored vehicles, brought other Azovstal fighters to a newly reopened prison in Olenivka near the regional capital Donetsk.

Moscow has depicted the Azov Regiment as one of the main perpetrators of the radical anti-Russian nationalism or even Nazism from which it says it needs to protect Ukraine's Russian-speakers.

State Duma (Russia’s lower house of parliament) Speaker Vyacheslav Volodin said: “Nazi criminals should not be exchanged.”

TASS news agency said Russian federal investigators would question the soldiers as part of a probe into what Moscow calls "Ukrainian regime crimes"

The Azov Regiment was formed in 2014 as an extreme right-wing volunteer militia to fight Russian-backed separatists who had taken control of parts of the Donbas - the largely Russian-speaking industrial heartland of eastern Ukraine.  

The regiment, however, denies being fascist, racist or neo-Nazi, and Ukraine says it has allegedly been reformed away from its radical nationalist origins to be integrated into the National Guard.

Interfax news agency, citing the Ministry of Justice website, reports that Russia's Prosecutor General's Office asked the Supreme Court to class the regiment as a “terrorist organization.”  

Lawmaker Leonid Slutsky, one of Russia's negotiators in talks with Ukraine, called the evacuated combatants "animals in human form" and said they should receive the death penalty.

"They do not deserve to live after the monstrous crimes against humanity that they have committed and that are committed continuously against our prisoners," he said.