Volodymyr Zelensky addresses UN, demands 'just punishment' for Russian crimes

President Volodymyr Zelensky demanded a special United Nations tribunal impose "just punishment" on Russia for its invasion of Ukraine, including financial penalties and stripping Moscow of its veto power in the Security Council.

Zelenskiy's recorded address to world leaders at the UN General Assembly came after Russian President Vladimir Putin ordered Moscow's first wartime mobilisation since World War II and threatened to use nuclear weapons to defend Russia in what he has cast as a defining East-West clash.

Moscow plans to conscript some 300,000 troops in an apparent escalation of its Ukraine invasion that began in February and has left thousands dead, displaced millions and reduced towns to rubble.

"A crime has been committed against Ukraine, and we demand just punishment," Zelensky told the UN body.

"A special tribunal should be created to punish Russia for the crime of aggression against our state... Russia should pay for this war with its assets," the Ukrainian president said, urging the UN to "remove the right of veto" from Russia as a Security Council member.

Zelenskiy laid out what he said were five non-negotiable conditions for peace. These included punishment for Russian aggression, restoration of Ukraine's security and territorial integrity, and security guarantees.

Many delegates at the UN gave Zelensky a standing ovation at the end of his speech. The Russian delegation remained seated.

New Zealand Prime Minister Jacinda Ardern, who partook in the standing ovation, described the president's speech as "powerful".

She earlier condemned Russia's threats to use nuclear weapons, which she said flew in the face of "the lie that they have told that they are there to liberate others".

"What we need here is a rallying cry from the world, what is happening in Ukraine is illegal, it's immoral, it's causing the loss of civilian life and that loss could extend if as Putin has claimed he broadens the types of weapons he uses in this war," she said.

Ardern held talks with Ukrainian Prime Minister Denys Shmyhal on the sidelines of the UN General Assembly.

Speaking before the sit-down, she told reporters she would seek Shmyhal's perspective on Putin's latest actions.

In an Instagram post afterwards, she said Shmyhal was "clear that New Zealand's contribution and response has been strong and appreciated".

She said she also met with Ukraine's First Lady, Olena Zelensky.

Australian foreign affairs Minister Penny Wong, who also attended the United Nations General Assembly, said: "These threats are unthinkable and they are irresponsible. His claims of defending Russia's territorial integrity are untrue. No sham referendum will make them true.

"Russia alone is responsible for this illegal and immoral war, and peace must first lie with Russia withdrawing from Ukrainian territory."

Seeking membership of the Western military alliance NATO and the European Union is enshrined in Ukraine's constitution. Russia said even before starting its invasion in February that NATO membership for Ukraine was a "red line" that could not be breached.

Ukraine and its Western allies have accused Russian forces of war crimes in different parts of the country they have occupied. Russia denies the allegations and says it does not target civilians.

Conscription and nuclear threat

Offering no evidence, Putin accused officials in NATO states of threatening to use nuclear weapons against Russia. They should know that "the weathervane can turn towards them", he said, adding that Russia "also has various means of destruction".

"When the territorial integrity of our country is threatened, we will certainly use all the means at our disposal to protect Russia and our people. It's not a bluff."

US President Joe Biden, in a speech to the UN General Assembly, responded: "Again, just today, President Putin has made overt nuclear threats against Europe, in a reckless disregard for the responsibilities of the non-proliferation regime."

Canadian Prime Minister Justin Trudeau condemned Putin's "irresponsible escalation of the war", saying "Putin's behaviour only goes to show that his invasion is failing."

Foreign ministers from the Group of Seven (G7) advanced economies confirmed in a meeting in New York their cooperation in extending support for Ukraine and responding to food and energy security, the Japanese Foreign Ministry said.

"It's clear Russia wants to destroy Ukraine," AEU foreign policy chief Josep Borrell said. "We will not be intimidated."

Russia and Ukraine also carried out an unexpected prisoner swap, the largest since the war began and involving almost 300 people, including 10 foreigners and the commanders who led a prolonged Ukrainian defence of Mariupol earlier this year.

The move comes at a time when Russia has been facing a string of battlefield failures, with its invasion force routed in northeastern Ukraine.

Ukrainian forces say they are now poised to push deeper into territory Moscow had captured over months of heavy fighting.

"No amount of threats and propaganda can hide the fact that Ukraine is winning this war, the international community are united and Russia is becoming a global pariah," said British Defence Secretary Ben Wallace.

Political risk

Russia's mobilisation may be the riskiest domestic political move of Putin's two decades in power, and followed months of Kremlin promises it would do no such thing.

The war has so far appeared to enjoy popular support in a country where independent media have all been shut down and public criticism of the "special military operation" is banned.

But for many ordinary Russians, especially in the urban middle classes, the prospect of being sent to fight would be the first hint of the war affecting them personally.

On the Moscow metro, men could be seen studying call-up papers.

"You always feel worried at moments like these. Because you have a wife and kids and you think about it," one resident told Reuters.

Several Western military experts said drafting hundreds of thousands of new troops would take months, do little to slow Russia's losses, and could even make matters worse by drawing resources away from the battlefield to train and equip recruits.

- Reuters, with additional reporting from RNZ