At least 20 countries have agreed to end financing for fossil fuel projects abroad, a UK official told CNN, in a deal expected to be announced this week. 

Another source close to the COP26 climate summit negotiations said that the US was party to the agreement. Officials at the US State Department did not immediately respond to CNN to confirm the country's involvement. 

Several countries had already agreed to end international financing for coal, but this agreement would be the first of its kind to include oil and gas projects as well. 

The deal "represents a change in norms that would have been unthinkable only a few years ago," Iskander Erzini Vernoit, a climate finance expert at think tank E3G, told CNN. "We've seen this go from the niche frontier concepts to at the core of the mainstream." 

In October, the UN Environment Programme's annual "production gap" report found 15 major fossil fuel-generating countries will produce roughly 110% more coal, oil, and gas in 2030 than what would be necessary to limit warming to 1.5 degrees Celsius above pre-industrial levels — and 45% more than what would be consistent with 2 degrees. 

A recent study published in the journal Nature found that a vast majority of the planet's remaining oil, natural gas, and coal reserves must remain in the ground by 2050 to avoid these consequences. Most regions around the world, according to the authors, must reach peak fossil fuel production now or within the next decade to limit the critical climate threshold. 

And the latest outlook by the International Energy Agency said that more aggressive climate action is needed from world leaders, even as the shift to clean energy leads to a decline in the oil industry. 

In a rare move during September's UN General Assembly in New York, Chinese President Xi Jinping announced the country will not build any new coal-fired power projects abroad. The vow marks a shift in policy around its sprawling Belt and Road infrastructure initiative, which had already begun to draw down its coal initiatives. 

Xi added that China will also increase financial aid for green and low-carbon energy projects for other developing countries. 

The production gap report found that the world's largest economies have funneled more than $300 billion in new funds toward fossil fuel activities since the onset of the Covid-19 pandemic, which is more than they have invested toward clean energy alternatives. 

"Modeling results show that all three fuels — coal, oil and gas — need to basically have started declining since 2020 in order for us to stay consistent with a pathway that will allow us to be consistent with limiting long-term warming to 1.5 degrees C," Ploy Achakulwisut, lead author of the report and scientist with the Stockholm Environment Institute, previously told CNN. "Continuing to delay action will just make the problem harder." 

- by Angela Dewan and Rachel Ramirez, CNN