Ukraine said it had damaged a Russian navy logistics ship near Snake Island, a small but strategic outpost in the Black Sea, while relatives of Ukrainian soldiers holed up in Mariupol's besieged steelworks pleaded for them to be saved.
Renewed fighting around Snake Island in recent days may become a battle for control of the western Black Sea coast, according to some defence officials, as Russian forces struggle to make headway in Ukraine's north and east.
"Thanks to the actions of our naval seamen, the support vessel Vsevolod Bobrov caught fire - it is one of the newest in the Russian fleet," said Serhiy Bratchuk, a spokesman for the Odesa regional military administration.
Reuters could not independently verify the details. Russia's defence ministry did not immediately respond to a request for comment.
Satellite imagery provided by Maxar, a private US-based company, showed the aftermath of what it said were probable missile attacks on a Russian Serna-class landing craft near the island, close to Ukraine's sea border with Romania.
Images also showed recent damage to buildings on the island, which became famous for the foul-mouthed defiance of its Ukrainian defenders early in the invasion.
Russia faced further setbacks on the battlefield as Ukraine drove its troops out of the region around the second-largest city Kharkiv, the fastest advance since forcing the Kremlin's forces from Kyiv and the northeast over a month ago.
Reuters journalists have confirmed Ukraine is now in control of territory stretching to the banks of the Siverskiy Donets River, around 40 km east of Kharkiv.
Footage released by Ukrainian Airborne Forces Command appeared to show several burnt-out military vehicles and a segment of a bridge seemingly destroyed and partially submerged in the river.
Regional authorities reported ongoing missile strikes around Poltava and shelling at Dergach, near Kharkiv, which killed two people.
In the capital Kyiv, wives and relatives of Ukrainian fighters holed up in the Azovstal steel plant in the southern port of Mariupol marched and chanted for their rescue. Russian forces have been bombarding the steelworks, the last bastion of Ukrainian defenders in a city almost completely controlled by Russia after a siege of more than two months.
Kyiv said it was working on a rescue of the servicemen, many badly injured.
"We have started a new round of negotiations around a road map for an (evacuation) operation. And we will start with those who are badly wounded," Deputy Prime Minister Iryna Vereshchuk told 1+1 television.