Russia is throwing "all the reserves they now have" at battles in Luhansk region, Ukrainian official says

 Russian and Ukrainian troops are engaged in a "fierce battle" on the outskirts of the Luhansk region in eastern Ukraine, according to Sheryl Heyday, the head of the Luhansk region's military junta.

"All the units of the Russian army are now being put there, all the reserves they have now," Heyday said on Tuesday.

Hayday claimed that Russian troops suffered "massive casualties" as some troops were tactically withdrawn to regroup.

"Hospitals are overcrowded, morgues are overcrowded," he said.

CNN was unable to independently confirm casualties on both sides.

Hayday added that "many warehouses behind enemy lines have been blown up" in recent days, destroying "a lot" of Russian munitions and fuel.

Hayday estimated that 10,000 to 15,000 residents remain in the city of Lysychansk.

The Ukrainian military announced on Sunday that it had been forced to withdraw from the city, and Ukrainian President Volodymyr Zelensky said the withdrawal was to save the lives of Ukrainian troops.

"They seek out pro-Ukrainian people, negotiate with collaborators, show apartments where military families live, break down doors and pull out clothes," Hayday said.

In a separate update on Tuesday, the Ukrainian Armed Forces General Staff said Russian troops were focusing "mainly" on controlling the highway connecting the cities of Lysychansk and Bakhmut and trying to invade the nearby settlement of Bilohorivka for conquest.