GLASGOW -- Poland, Vietnam, Chile and other countries will pledge on Thursday to phase out coal-fuelled power generation and stop building new plants, in a deal the COP26 summit's British hosts said would commit 190 nations and organisations to quit the fuel.

Coal is the most polluting fossil fuel and greenhouse gas emissions from burning it are the single biggest contributor to climate change. Weaning the world off coal is seen as vital to achieve globally agreed climate targets.

Signatories of the COP26 agreement would commit on Thursday to shun investments in new coal plants at home and abroad, and phase out coal-fuelled power generation in the 2030s in richer countries, and the 2040s for poorer nations, the British government said.

"The end of coal is in sight. The world is moving in the right direction, standing ready to seal coal’s fate and embrace the environmental and economic benefits of building a future that is powered by clean energy," British business and energy secretary Kwasi Kwarteng said.

Separately, the Powering Past Coal Alliance - an international campaign aimed at phasing out the fuel - said it had secured 28 new members, including Ukraine, which pledged to quit the fuel by 2035. Coal produced roughly a third of Ukraine's power last year.

Factors including concerns over planet-warming pollution and a worsening economic profile for coal-fuelled generation have curbed its share in wealthy western countries including Britain, Germany and Ireland over the last few decades.

But coal still produced around 37% of the world's electricity in 2019, and a cheap, abundant local supply means the fuel dominates power production in countries including South Africa, Poland and India. These countries will require huge investments to shift their industries and energy sectors onto cleaner sources.

The global pipeline for new coal power projects has shrivelled in recent years, although China, India, Vietnam and Indonesia are among those planning to build new coal plants.

Britain did not confirm if those countries would be involved in the COP26 coal phase out pledge, or if Vietnman's pledge on Thursday would affect its pipeline of coal projects already in the pre-construction stage.

China said in September it would stop funding overseas coal plants, although the pledge did not cover domestic projects.

A raft of finance announcements are expected at COP26 on Thursday to accompany the coal pledges - both through new investments in clean power, and funds to support workers and regions that depend on the coal sector for their livelihoods.

Countries including Britain and the United States announced a $8.5 billion partnership with South Africa at the COP26 conference on Tuesday, to help the country phase out coal faster.