Hundreds of civil society groups and NGOs Friday called on governments worldwide to "reject and ban any import of fossil fuels from Russia" in order to cut off the main source of revenue for Vladimir Putin's invasion of Ukraine.

It is "clear that this war machine has been funded, fed and fuelled by the coal, oil and gas industries that are driving both the invasion threatening Ukraine and the climate crisis threatening humanity's future," they said in an open letter.

"Putin's income streams must be dried out as soon as possible," said the letter, signed by the World Council of Churches,, Greenpeace and CAN International, an umbrella organisation of more than 1,500 climate NGOs.

Approximately 40 percent of Russia's federal budget comes from oil and gas revenues, which also make up about three-fifths of Russian exports.

"Putin has deliberately weaponized fossil gas to increase his existing energy dominance over the European Union and to threaten European nations that would come to Ukraine's aid," the letter said. "This needs to stop!"

Some 40 percent of Europe's natural gas needs are supplied by Russia, with Germany, Hungary and Slovakia especially dependent.

"We call on you to urgently work with your European colleagues on ending this fossil fuel addiction once and for all," said the letter, addressing other importers of Russian oil and gas, such as the United States, Canada, China, India and Japan.

Some 40 percent of Europe's natural gas needs are supplied by Russia
Some 40 percent of Europe's natural gas needs are supplied by Russia AFP / Kenzo TRIBOUILLARD

The signatories also included Ukrainian officials and numerous civil society organisations.

Roman Shakhmatenko, Ukraine's deputy environment minister, called on the world to "stop being indifferent".

Countries should not simply replace Russian-produced fossil fuels with coal, oil and gas from other countries in order to avoid the worst ravages of global warming, the NGOs warned.

A landmark UN report on climate impacts released this week reports a measurable increase in deadly storms, heatwaves, droughts and rainfall events all made worse by rising temperatures, with projections of far worse to come.

On the last day of the 195-nation closed-door conference leading up to the report's release, Ukraine's head of delegation made a similar plea.

"We will not surrender in Ukraine, and we hope the world will not surrender in building a climate resilient future," Svitlana Krakovska told the closing plenary in English, according to multiple sources.

"Human-induced climate change and the war on Ukraine have the same roots -- fossil fuels -- and our dependence on them."