A Russian missile strike in Ukraine's southern port of Odesa early on Friday killed at least 10 people, a regional official said, a day after Ukraine drove Russian forces from the strategic Black Sea outpost of Snake Island.

Earlier reports said six people had died in the night-time strike on a residential building, including three children.

"The number of dead as a result of a strike on a multi-story apartment building has now risen to 10," Serhiy Bratchuk, spokesperson for the Odesa regional administration said on his Telegram channel.

Reuters could not independently confirm details of the incident.

It came after Russia on Thursday said it had decided to withdraw from Snake Island as a "gesture of goodwill" to show Moscow was not obstructing U.N. attempts to open a humanitarian corridor allowing grains to be shipped from Ukraine.

Ukraine said it had driven Russian forces off the outcrop after an artillery and missile assault, with President Volodymyr Zelenskiy hailing the strategic win.

"It does not yet guarantee security. It does not yet ensure that the enemy will not come back," he said in his nightly video address. "But this significantly limits the actions of the occupiers. Step by step, we will push them back from our sea, our land and our sky."

In contrast, however, Ukrainian forces were desperately hanging on against Russia's superior firepower in the city of Lysychansk.

Russian artillery shelled from different directions while the Russian army approached from several sides, regional Governor Serhiy Gaidai said on Ukrainian television.

"The superiority in fire power of the occupiers is still very much in evidence," Zelenskiy said. "They have simply brought in all their reserves to hit us."

Russian forces have been trying to encircle Lysychansk since they captured Sievierodonetsk, on the opposite side of the Siverskyi Donets River, last week after weeks of heavy fighting.

In Sievierodonetsk, residents have emerged from their basements and are sifting through the rubble of their ruined city as they look to rebuild.

"Almost all the city infrastructure is destroyed. We are living without gas, electricity, and water since May," Sergei Oleinik, a 65-year-old resident told Reuters. "We are glad that this ended, and soon maybe reconstruction will start, and we will be back to more or less normal life."

SUPPORT FOR UKRAINE

Despite yielding ground and taking punishing losses in the eastern Donbas in recent weeks, Ukraine hopes to inflict enough damage to exhaust Russia's advancing army and have counter-attacked in the south of the region.

Ukraine's Western allies have been sending weapons and the Kyiv government was given another boost with the United States saying it would provide a further $800 million in weapons and military aid.

U.S. President Joe Biden, speaking after a NATO summit in Madrid, said Washington and its allies were united in standing up to Russian President Vladimir Putin.

"I don't know how it's going to end, but it will not end with Russia defeating Ukraine," Biden told a news conference. "We are going to support Ukraine for as long as it takes."

SMOKE AND FIRE

Ukrainian forces in the "south" district of the Joint command of the Ukrainian armed forces killed 35 Russian servicemen and put out of action two tanks and four armoured vehicles, according to a Ukrainian military statement on Facebook on Friday.

"The Ukrainian armed forces are not only holding defence lines but also engaging in successful operations aimed at liberating occupied towns in Kherson region from the invaders," Kriviy Rih regional Governor Oleksandr Vilkul said on Telegram, adding Ukrainian troops had taken back the town of Potyomkin.

Reuters could not immediately verify battlefield claims.

Snake Island was retaken by Ukraine after weeks in which momentum in the four-month-old conflict appeared to be shifting in favour of Russia.

The Ukrainian military posted an image on Facebook of what appeared to be the island, seen from the air, with several columns of black smoke rising above it.

"The enemy hurriedly evacuated the remains of the garrison with two speed boats and probably left the island. Currently, Snake island is consumed by fire, explosions are bursting," it said.

Ukrainian Brigadier General Oleksii Hromov said Ukrainian forces were not yet occupying the island but would do so.

The rocky outcrop overlooks sea lanes to Odesa, Ukraine's main Black Sea port, where Russia is blocking food cargos from one of the world's leading grain suppliers.

Snake Island captured world attention after Russia seized it on the first day of what it describes as a "special operation" to disarm dangerous nationalists. A Ukrainian guard, ordered by Russia's flagship cruiser Moskva to surrender, radioed back "Russian warship: go fuck yourself".

Lifting the blockade has been a primary goal of the West. U.S. Secretary of State Antony Blinken has accused Russia of deliberately causing world hunger as "blackmail".

Moscow denies blocking the ports and blames food shortages on Western sanctions it says limit its own exports.

Russia had defended the island since February despite Ukraine claiming to inflict severe damage, sinking supply vessels and destroying Russian fortifications.

Reuters