Ukraine is using captured Russian tanks to consolidate its gains in its north-east amid an ongoing counter-offensive, according to a US-based think tank.
It comes as Kyiv vowed to push further into territories occupied by Moscow.
The Institute for the Study of War, citing a Russian claim, said Ukraine has been using abandoned Russian T-72 tanks as it tries to push into the Russian-occupied region of Luhansk.
"The initial panic of the counter-offensive led Russian troops to abandon higher-quality equipment in working order, rather than the more damaged equipment left behind by Russian forces retreating from Kyiv in April, further indicating the severity of the Russian rout," the institute said.
Earlier this month, Ukraine launched its counter-offensive, pushing into territory around its second-largest city of Kharkiv.
Videos and photos showed Ukrainian troops seizing tanks, ammunition and other weaponry left behind by Moscow in a seemingly chaotic withdrawal.
Burial sites have been found in some areas where Russian forces were pushed out by Ukrainian troops, most notably in the city of Izium, where Ukrainian officials said hundreds of graves were found.
Yevhenii Yenin, a deputy minister in Ukraine's Internal Affairs Ministry, told a national telecast officials exhuming the dead found bodies "with signs of violent death".
"There are many of them," Mr Yenin said.
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Ukrainian officials have also accused Russian forces of torturing people in occupied areas, including shocking them with radio telephones dating back to the Soviet era.
Russia has repeatedly denied abusing or killing prisoners, though Ukrainian officials found mass graves around the city of Bucha after blunting a Russian offensive targeting Kyiv at the start of the war.
Meanwhile, a Ukrainian push continues in the south of the country.
The Washington-based institute, citing the Ukrainian military, said Kyiv has destroyed ammunition depots, two command posts and an electronic warfare system.
Ukraine's southern military command said early on Tuesday its troops sank a Russian barge carrying troops and weapons across the Dnipro River near the Russian-occupied city of Nova Kakhovka.
It offered no other details on the sinking of the barge in Ukraine's Russian-occupied Kherson region, which has been a major target as part of Kyiv's ongoing counter-offensive in the country.