Numerous diplomats walked out on Tuesday when Russia's foreign minister addressed the UN Human Rights Council, after a similar boycott of his speech at the nearby Conference on Disarmament.

The diplomats filed out of the room when Sergei Lavrov's pre-recorded video message began to play, in protest against Moscow's invasion of Ukraine, according to an AFP journalist in the room.

Malta's ambassador to the United Nations, Chris Grima, was among the more than 100 diplomats who walked out.

Ambassador Grima (centre) was among those who walked out.

"Thank you very much for this wonderful show of support to Ukrainians who are fighting for their independence," Ukrainian Ambassador Yevheniia Filipenko, who led the walkout, told the crowd gathered around a large Ukrainian flag outside the chamber. 

"Any invasion constitutes a violation of human rights... massive violations and civilian losses," French Ambassador Jerome Bonnafont said.

"It is important that the Human Rights Council shows with this walkout that it is united with Ukraine and with the people of Ukraine."

The fresh walkout came less than an hour after diplomats all but emptied a nearby room at the UN's European headquarters in Geneva when Lavrov's video speech aired to the Conference on Disarmament, a body created in 1979 to try to stem the Cold War arms race.

Outside that chamber, diplomats also gathered in front of a Ukrainian flag and applauded loudly.

The applause could be heard in the chamber where Lavrov's speech continued, with only a handful of ambassadors from countries including Yemen, Syria, Venezuela and Tunisia there to hear it.

'War crimes' 

Russia's top diplomat had been scheduled to come to Geneva to address both the UN-linked disarmament body and the UN Human Rights Council in person on Tuesday.

But he cancelled at the last minute, with Moscow blaming "anti-Russian sanctions" imposed by EU countries.

Russia has become an international pariah since it launched a full-scale invasion six days ago, with its forces killing dozens on the streets of Ukraine's cities and forcing hundreds of thousands to flee.

The morning meeting of the disarmament conference kicked off with a minute of silence for the "victims" in Ukraine. 

"Russian indiscriminate attacks on civilian and critical infrastructure are war crimes and violations of the Rome Statute," Ukraine's foreign minister Dmytro Kuleba told the meeting.

The Rome Statute is the treaty that established the International Criminal Court.

"Russian aggression is a global threat," Kuleba warned. "The response too must be global."

He said Ukraine had called for a special plenary meeting on the crisis at the Conference for Disarmament but it remained unclear whether this would go ahead.

Kyiv meanwhile succeeded on Monday to secure support for an urgent debate at the UN human rights council later this week. It will seek the creation of a high-level investigation into violations committed in the conflict, dating back to Russia's annexation of Crimea in 2014. 

In his speech at the Conference on Disarmament, Lavrov meanwhile blamed Kyiv for the crisis and said Ukraine was trying to assemble nuclear weapons.

"I can assure you, Russia as a responsible member of the international community... is taking all necessary measures to prevent the emergence of nuclear weapons and related technologies in Ukraine," he said.