KYIV/BRUSSELS: Russia unleashed a barrage of missiles on the Ukrainian city of Mykolaiv on Thursday, officials said, after the United Nations General Assembly condemned Moscow's attempted annexation of four Ukrainian areas and Kyiv's allies committed more military aid.

"A five-storey residential building was hit, the two upper floors were completely destroyed, the rest – under rubble. Rescuers are working on the site,” Mayor Oleksandr Senkevich said in a social media post, adding the southern city was "massively shelled".

A shipbuilding centre and a port on the Southern Bug river off the Black Sea, Mykolaiv has suffered heavy Russian bombardments throughout the war.

In New York, three-quarters of the 193-member General Assembly - 143 countries - voted on Wednesday in favour of a resolution that called Moscow's move illegal, deepening Russia's international isolation.

Only four countries joined Russia in voting against the resolution - Syria, Nicaragua, North Korea and Belarus. Thirty-five countries abstained from the vote, including Russia's strategic partner China, while the rest did not vote.

Ukrainian President Volodymyr Zelenskiy said on Twitter he was "grateful to 143 states that supported historic #UNGA resolution ...(Russia's) attempt at annexation is worthless."

In Brussels, more than 50 Western countries met to pledge more military aid to Ukraine, especially air defence weapons, on the heels of heavy retaliatory strikes this week ordered by Russian President Vladimir Putin in response to an explosion on a bridge in Crimea.

Pledges from allies included an announcement by France that it would deliver radar and air defence systems to Ukraine in the coming weeks. Britain pledged air defence missiles, and Canada said it would provide artillery rounds among other supplies.

At the meeting of the Ukraine Defence Contact Group in Brussels, U.S. Defence Secretary Lloyd Austin said Russia's latest attacks laid bare its "malice and cruelty" since invading Ukraine on Feb. 24. At least 26 people have been killed since Monday in Russian missile attacks across Ukraine.

Ukraine had shifted momentum since September with extraordinary gains, but would need more help, he said. "...We're going to do everything we can to make sure that they have what's required to be effective," Austin told reporters.

ZELENSKIY SAYS AID WILL HASTEN WAR'S END

Since Monday's attacks, Germany has sent the first of four IRIS-T SLM air defence systems, while Washington said it would speed up delivery of a promised NASAMS air defence system.

Zelenskiy said the increased aid would strengthen the counteroffensive.

"The more assistance Ukraine gets now, the sooner we'll come to an end to the Russian war," Zelenskiy said by video to a forum during International Monetary Fund and World Bank annual meetings in Washington.

Moscow in September proclaimed its annexation of four partially occupied regions in Ukraine - Donetsk, Luhansk, Kherson and Zaporizhzhia - after staging what it called referendums. Ukraine and allies have denounced the votes as illegal and coercive.

The General Assembly vote followed a veto by Russia last month of a similar resolution in the 15-member Security Council.

Russia's U.N. Ambassador Vassily Nebenzia told the General Assembly ahead of the vote that the resolution was "politicized and openly provocative," adding that it "could destroy any and all efforts in favour of a diplomatic solution to the crisis."

The moves at the United Nations mirror what happened in 2014 after Russia annexed Ukraine's Crimea. The General Assembly then adopted a resolution declaring the referendum invalid with 100 votes in favour, 11 against and 58 formal abstentions.

The United States and other Western countries lobbied ahead of Wednesday's vote. They won dozens more votes than compared with the 2014 result, and improved on the 141 countries who voted to denounce Russia and demand it withdraw its troops from Ukraine within a week of its invasion.

DEATHS REPORTED AT AVDIIVKA MARKET

Air raid sirens sounded across parts of Ukraine for a third day on Wednesday. The Ukrainian governor of partially occupied Donetsk province said seven people were killed in Russian shelling of a market in the frontline town of Avdiivka. Reuters was not able to verify battlefield reports.

There were reports of some shelling elsewhere, but no sign of the countrywide strikes of the previous two days. Pope Francis denounced the bombings, part of what he called a "hurricane of violence".

Ukraine's military said its forces consolidated control of several settlements recaptured from Russian troops on the west bank of the Dnipro River, near the Russian-occupied town of Beryslav in the Kherson region.

Transatlantic alliance NATO's secretary-general, Jens Stoltenberg, said Russia's missile attacks were a sign of weakness. "Russia is actually losing on the battlefield," Stoltenberg said.

As his forces have lost ground since September, Putin has intensified the conflict, ordering the call-up of hundreds of thousands of reservists, proclaiming the annexation of occupied Ukrainian territory and repeatedly threatening to use nuclear weapons to protect Russia.

U.S. President Joe Biden said on Wednesday he doubted Putin would resort to that. Putin is a "rational actor who has miscalculated significantly", he told CNN, saying he believed the Russian leader had expected his invading troops to be welcomed.

A senior NATO official said a Russian nuclear strike would change the course of the conflict and almost certainly trigger a "physical response" from Ukraine's allies - "and potentially from NATO itself."

Zelenskiy said Ukraine needed about $55 billion in financial support next year - $38 billion to close the budget deficit and $17 billion to rebuild critical infrastructure such as schools and housing.