Thursday saw further undiplomatic words at the United Nations General Assembly as leaders reacted to Russia's nuclear sabre-rattling over Ukraine.

"The very international order we've gathered here to uphold is being shredded before our eyes," US Secretary of State Antony Blinken told the gathering in New York. "We can't let President Putin get away with it."

UN chief Antonio Guterres warned that talk of nuclear conflict was "totally unacceptable".

And he was deeply concerned about Russia's plans for so-called referendums on joining Russia in occupied parts of Ukraine, saying the annexation of a country's territory through force - or the threat of it - was a violation of the UN charter.

But Sergei Lavrov, Russia's foreign minister, used his speech to attack Ukraine in turn - accusing the West of "connivance" with human rights groups in "covering the crimes of the Kyiv regime".

US national security spokesman John Kirby told the BBC that Mr Putin's threat to use all means to defend Russian territory was being taken "seriously".

Meanwhile, President Putin's decision to call-up an estimated 300,000 Russian reservists to fight in Ukraine has led to fears the war will escalate further - and has proven controversial in Russia too