Russian troops are engaged in heavy fighting and making their way into Ukraine's Donetsk region after taking control of the last two towns in neighboring Luhansk, the regional governor of Luhansk said on Tuesday.
Serhiy Gaidai said the Russian troops had sustained heavy losses in the long process of capturing the twin towns of Sievierodonetsk and Lysychansk, but were channeling their efforts into moving southward.
"Heavy fighting is going on at the edge of Luhansk region... All the forces of the Russian army and reserves have been redirected there... They are sustaining heavy losses," Gaidai told Ukrainian television.
"A large quantity of equipment is being sent towards Donetsk region. Of course, after Luhansk region, Donetsk is at the top of their list."
Reuters could not verify Gaidai's statements about the Russian advance.
After failing to move on Kyiv at the start of its invasion, the Kremlin said it had redirected its forces to Donbas - Ukraine's industrial heartland made up of Luhansk and Donetsk.
Russian proxies have held large swathes of both regions since Moscow first advanced into Ukraine in 2014 and Moscow recognized two "people's republics" as independent states on the eve of the February invasion. Moscow on Sunday claimed the "liberation" of the entire Luhansk region.
Some analysts say Russia concentrated more than half of its fighting force in launching the drive to capture Luhansk.
Ukraine still controls much of Donetsk and any Russian advance would involve taking a half dozen large industrial towns, starting with Bakhmut, Sloviansk and Kramatorsk.
Gaidai said Russian losses in the fighting were so severe that "they are not taking all their wounded with them. The hospitals are full to bursting as are the morgues.
"Our forces have been hitting their depots away from the front lines. A great deal of equipment and fuel needed for equipment is being destroyed. So we can assume that they will have to take a breather at some point."
Gaidai said up to 15,000 people remained in Lysychansk, site of an oil refinery. And Russian forces, he said, were engaged in retribution against pro-Ukrainian residents.
"They are looking for pro-Ukraine residents, they are making deals with collaborators, they are identifying apartments where servicemen lived," he said. "Everything is being destroyed. Entire book collections in Ukrainian."