KYIV: Russian missiles hit an apartment building and a resort near Ukraine's Black Sea port of Odesa on Friday, killing at least 17 people and wounding dozens, Ukrainian authorities said.

Thousands of civilians have been killed since Russia invaded Ukraine on Feb. 24 in what Ukraine says is an unprovoked war of aggression. Russia denies targeting civilians and says it hits only military infrastructure in what it calls a "special operation" to root out dangerous nationalists.

With its ground forces concentrated in Ukraine's eastern industrial region of Donbas, Russia has more than doubled the number of missile strikes around the country in the past two weeks, using inaccurate Soviet-era missiles for more than half of the attacks, according to a Ukrainian brigadier general. 

One missile struck a nine-story building in the town of Bilhorod-Dnistrovskyi at about 1 a.m. (2200 GMT Thursday), the Ukrainian emergencies ministry said. It also caused a fire in an attached store building.

Serhiy Bratchuk, spokesperson for the Odesa regional administration, told Ukrainian state television a rescue operation was under way as some people were buried under rubble after part of the building collapsed.

Another missile hit a resort facility, Bratchuk said, killing at least three people including a child and wounding one person.

Reuters could not independently confirm details of the incident.

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

Ukraine said it had driven Russian forces off the Black Sea outcrop after an artillery and missile assault, with President Volodymyr Zelenskiy hailing a 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 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 basements and are sifting through the rubble of their ruined city.

"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.

Ukraine's Western allies have been sending weapons and the 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 America 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."

As well as providing weapons, the United States and allies have imposed punishing sanctions on Russia and many Western companies have withdrawn from it or are planning to.

Russia has taken control of some assets and on Thursday moved to create a new firm to take charge of the giant Sakhalin-2 gas and oil project in its far east, knocking shares in the Japanese companies that own part of the project.

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, the Ukrainian military said in a statement on Facebook.

"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.

Ukrainian Brigadier General Oleksii Hromov said Ukrainian forces had not occupied the island but would do so.

Russia denies blocking Ukraine's ports and blames food shortages on Western sanctions it says limit its exports.

Speaking in Moscow on Thursday, Indonesian leader Joko Widodo offered to be a diplomatic bridge between Putin and his Ukrainian counterpart, and said he hoped global food and fertiliser supply lines could be reinstated.

"I really appreciate President Putin who said earlier that he will provide a security guarantee for food and fertiliser supplies from both Russia and Ukraine. This is good news," he said.