The war in Ukraine entered its second year on Friday with no end in sight and Russia isolated at the United Nations in a vote demanding its forces withdraw, while G7 leaders are set to coordinate more help for Ukraine.

As fighting raged on in Ukraine's east and south, its allies around the world showed their support on the first anniversary of Russia's invasion.

Paris lit up the Eiffel Tower in the Ukrainian flag colours of blue and yellow and people draped in Ukrainian flags gathered at a vigil in London. In Brussels, European Union buildings were similarly lit up in the colours.

The UN General Assembly overwhelmingly adopted a resolution on Thursday marking the war's anniversary and demanding Russia pull out and stop fighting.

There were 141 votes in favour, including Malaysia, and 32 abstentions. Six countries joined Russia to vote no - Belarus, North Korea, Eritrea, Mali, Nicaragua, and Syria.

Russia's ally China abstained from the UN vote.

Russia's Deputy UN Ambassador Dmitry Polyanskiy dismissed the action at the United Nations as "useless".

Ukrainian President Volodymyr Zelenskiy hailed the vote.

"This resolution is a powerful signal of unflagging global support for Ukraine," he said in a post on Twitter.

On the battlefield, the Ukraine military reported increased Russian activity in the east and south as the anniversary approached, with at least 25 towns and villages in three northern regions along the Russian border under fire.

Reuters was not able to verify battlefield reports.

Russian President Vladimir Putin had ordered a full-scale invasion of Ukraine on Feb 24 last year to seize Kyiv and topple the pro-European government, but those hopes were dashed by a fierce defence and military blunders that embarrassed Moscow.

Ukraine had success with counter-offensives in late 2022 to grab back much of the territory it had lost. Russia now controls around a fifth of Ukraine.

Trench warfare

The war, which Russia calls a "special military operation" to protect its sovereignty, has settled into attritional trench warfare, with rising losses on both sides, particularly this year in fighting in and around the eastern town of Bakhmut.

Some US and Western officials estimate Russia's casualties at nearly 200,000 dead and wounded, while in November the top US general said more than 100,000 troops on each side had been killed or wounded.

It is impossible to independently verify casualties in what has become the worst conflict in Europe since World War Two.

Millions of Ukrainians have fled their country and tens of thousands of civilians have been killed.

The village of Bucha in the north near Kyiv, where mass graves were discovered, and the bombed-out southern city of Mariupol became symbols of what Ukraine and its allies described as Russian brutality.

Ukraine and the West have accused Russia of war crimes, but Moscow denies targeting civilians.

Far from the military campaigns, the war has damaged the world economy and a Cold War chill has set into international relations, with Putin raising the spectre of nuclear weapons and signalling a desire to double down on a conflict that prompted tough Western sanctions.

With Zelenskiy insisting on his country's sovereignty and Moscow's withdrawal, the prospects of peace appear bleak.

"We don't know when the war will end. But what we do know is that when the war ends, we need to ensure that history doesn't repeat itself," NATO secretary-general Jens Stoltenberg told Reuters on Thursday.

"We need to ensure that we break the cycle of Russian aggression. We need to prevent Russia from chipping away at European security," he said.

Support for Ukraine

US President Joe Biden will meet virtually on Friday with G7 leaders and Zelenskiy to mark the anniversary and announce new sanctions against those aiding Russia's war effort, the White House said.

White House National Security Adviser Jake Sullivan said the United States would provide an additional US$2 billion in security assistance.

The United States has said China is considering providing weapons to Russia, which could intensify the conflict into a confrontation between Russia and China on one side and Ukraine and the US-led NATO on the other.

Beijing's top diplomat visited Moscow this week and pledged a deeper relationship between the countries and Putin on Thursday hailed "new frontiers" in ties and signalled China's leader Xi Jinping would visit.

Xi is expected to deliver a "peace speech" on Friday, though some analysts have cast doubt on whether China's efforts to act as peacemaker will go beyond rhetoric.

The Chinese Foreign Ministry said in a position paper on Friday that dialogue and negotiation were the only viable ways to resolve the conflict.

"Conflict and war benefit no one. All parties must stay rational and exercise restraint, avoid fanning the flames and aggravating tensions, and prevent the crisis from deteriorating further or even spiralling out of control," the ministry said.

Reflecting the Kremlin's increasingly hawkish tone, Russian Defence Minister Sergei Shoigu on Thursday cast the war as an existential fight against a hostile West.

Ukraine and its allies say the invasion is an unjustified land grab aimed at subjugating a sovereign state.

Further ratcheting up tension, Putin announced plans on Thursday to deploy new Sarmat multi-warhead intercontinental ballistic missiles this year. This week, he suspended Russia's participation with the United States in the New Start, or Strategic Arms Reduction Treaty, a nuclear arms control treaty.

Russia's military focus is on seizing the eastern Ukrainian regions of Donetsk and Luhansk, which together form the industrial area known as the Donbas near the Russian border.

Close to a Ukrainian tank park near Bakhmut, which has become Russia's main target, constant explosions could be heard on Thursday.

"If we give up Bakhmut, everything else will get even more complicated. We can't give it up, under any circumstance. We will hold through," Junior Sergeant Oleh Slavin, a tank operator, told Reuters.

- Reuters