China and India will need to explain to developing nations why they pushed to water down language on efforts to phase out coal at the COP26 conference, the event's president Alok Sharma said on Sunday.
UN climate talks in Glasgow, Scotland, ended on Saturday with a deal that targeted fossil fuels for the first time.
But India, backed by China and other coal-dependent developing nations, rejected a clause calling for a "phase out" of coal-fired power, and the text was changed to "phase down".
"In terms of China and India, they will on this particular issue have to explain themselves," Sharma told a news conference at Downing Street in London.
British Prime Minister Boris Johnson said: "Whether the language was 'phase down' or 'phase out' doesn't seem to me as a speaker of English to make that much difference.
"The direction of travel is pretty much the same."
Johnson said COP26 had delivered a mandate to cut the use of coal-powered generation that was backed up by real action from individual counties.