The BBC has learned that COP26 organisers would not allow the Chinese President, Xi Jinping, to address the conference by video link.
The incident underlines the difficulty of bringing world leaders together to solve the crisis.
The UK, which is hosting the summit, believed it was critical for world leaders to attend the conference in person.
President Xi, however, has not left China since the Covid pandemic took hold, and declined to attend. Instead, he expected to appear by video link.
But the meeting organisers only gave him the option of providing a written statement, which he supplied.
For many, it seemed a small contribution from the world’s biggest emitter of greenhouse gases, particularly as the statement contained no new pledges.
The conference organisers issued a statement suggesting some frustration at China’s approach.
