The prime minister exchanged harsh words with the Russian foreign minister (Photo: PA)

Rishi Sunak said that “countries should not invade their neighbours” while condemning Russia’s invasion of Ukraine at the G20 summit in Bali.

Speaking to Russian Foreign Minister Sergei Lavrov, the prime minister urged Moscow to “get out of Ukraine and end this barbaric war”, blaming the conflict for worsening global economic challenges.

He criticized President Vladimir Putin for avoiding the meeting, saying “if he had, maybe we could go ahead with the settlement.”

The two-day gathering of leaders of the world’s major economies was opened by Indonesian President Joko Widodo, who said the world will struggle to move forward “if the war doesn’t end”.

The annual summit comes at a time when G20 nations are deeply divided over Russia’s actions in Ukraine, which have driven up food and energy prices around the world.

In his remarks, Mr Sunak said the context for this G20 was “dark”.

According to a Downing Street transcript of his speech to the closed session, the Prime Minister said: “Russia’s illegal invasion of Ukraine has profound consequences for all of us, as it has undermined fundamental principles of sovereignty and territorial integrity.

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“We all rely on these principles. They are the foundations of the international order. They need to be taken care of.

NUSA DUA, INDONESIA - NOVEMBER 15: Prime Minister Justin Trudeau of Canada (2L), British Prime Minister Rishi Sunak (2R) and FIFA President Gianni Infantino (R) speak before a working lunch at the G20 summit on November 15, 2022 in Nusa Duo , Indonesia.  Britain's new prime minister wants to voice his views on foreign policy while grappling with economic instability at home.  (Photo by Leon Neal/Getty Images)

The prime minister met world leaders at the G20 summit in Egypt (Photo: Getty)

15-11-2022.  Bali, Indonesia.  Prime Minister Rishi Sunak attends the G20 leaders luncheon where he spoke with German Chancellor Olaf Scholz, Canadian Prime Minister Justin Trudeau, Indian Prime Minister Narendra Modi and others.  Photo by Simon Walker / No. 10 Downing Street

Prime Minister Rishi Sunak chatted with Chancellor Olaf Scholz, Canadian Prime Minister Justin Trudeau, Indian Prime Minister Narendra Modi and others (Photo: Simon Walker / No10 Downing Street)

“It’s very simple: countries must not raid their neighbours, they must not attack civilian infrastructure and civilian populations, and they must not threaten nuclear escalation.”

He said the economic problems “that we should be focusing on today have become much, much worse” because of Moscow’s actions.

“Weaponizing energy and food is totally unacceptable,” he said, adding that Russia is “harming the most vulnerable people around the world” by destroying grain supplies and blocking shipments.

Sunak called on his fellow leaders to support the extension of a deal that would allow the export of grain from Ukraine’s Black Sea ports to ease the global food crisis.

He continued, “One man has the power to change all this.

“It is remarkable that Putin could not come with us. If so, maybe we can continue figuring things out.

“Because the biggest difference anyone can make is for Russia to get out of Ukraine and end this barbaric war.”

The prime minister said he “rejects this aggression” while vowing to “support Ukraine as long as possible”.

He praised Volodymyr Zelenskyy’s “incredible fortitude” after the Ukrainian president spoke via video link at the Bali summit at the invitation of the Indonesian hosts.

Mr Sunak is holding a series of bilateral meetings on the sidelines of the event, which began shortly after the Prime Minister’s arrival on the tropical island on Monday over drinks and canapés with his Canadian counterpart Justin Trudeau.

More controversially, he is meeting today with Saudi Crown Prince Mohammed bin Salman, who is widely believed to have been involved in the 2018 murder of Saudi journalist Jamal Khashoggi.

He also has one-on-one talks on Wednesday with US President Joe Biden, Indonesia’s Mr Widodo, Indian Prime Minister Narendra Modi, Japanese Prime Minister Fumio Kishida and Australia’s new Prime Minister Anthony Albanese.

Mr Sunak will return to the UK on Thursday in time for his budget which could lead to Jeremy Hunt imposing up to £60bn in tax increases and austerity.