Russia’s invasion of Ukraine is a violation of the founding United Nations Charter and international law, UN Secretary-General Antonio Guterres says, as he calls out Russian threats about the possible use of nuclear weapons.

Since Moscow invaded its neighbour on February 24 last year, Russian President Vladimir Putin has repeatedly hinted Russia could use a nuclear weapon if threatened.

“We have heard implicit threats to use nuclear weapons,” Mr Guterres told the 193-member UN General Assembly at a meeting to mark the first anniversary of the war in Ukraine.

“The so-called tactical use of nuclear weapons is utterly unacceptable.

“It is high time to step back from the brink.”

The General Assembly is set to adopt a draft resolution – likely on Thursday – stressing “the need to reach, as soon as possible, a comprehensive, just and lasting peace” in line with the UN Charter.

Mr Guterres described the UN Charter as “unambiguous”, citing: “All members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state.”

Ukraine and its supporters hope to deepen Russia’s diplomatic isolation by seeking yes votes from almost three-quarters of the General Assembly to match – if not better – the support received for several resolutions last year.

“The position of the United Nations is unequivocal: We are committed to the sovereignty, independence, unity and territorial integrity of Ukraine, within its internationally recognised borders,” Mr Guterres said.

The draft text would again see the General Assembly demand Moscow withdraw its troops and call for a halt to hostilities. General Assembly resolutions are non-binding, but carry political weight.

Russia has urged UN states to vote against an “unbalanced and anti-Russian” move.

Ukrainian Foreign Minister Dmytro Kuleba said Ukraine was exercising its right to self-defence as enshrined in the UN Charter and that “when you are sending weapons to Ukraine, you are helping Ukraine to defend UN Charter”.

“Russia violated the UN Charter by becoming an aggressor,” he said at the United Nations.

“When you are sending weapons to them, you are helping to destroy the UN Charter and everything that the United Nations stand for. It’s very simple.”

Russia has said it launched a “special military operation” to “denazify” Ukraine and protect Russian speakers.

It has also accused the West of waging a “proxy war” against it by arming Ukraine and imposing sanctions on Moscow.

The US and its Western allies have called the invasion an unprovoked land grab against a sovereign nation.

– AAP