'Pig looking in mirror'

Su earlier referred to a Chinese saying that roughly translates as "a pig looking in a mirror" with reference to the United States and what he said was Washington's refusal to acknowledge its own faults.

But Christiana Figueres, the executive secretary of the UN's Framework Convention on Climate Change. said the rift had not derailed the Tianjin talks and that important progress had been made on specific issues.

"I would dare say that this week has got us closer to a structured set of decisions that can be agreed in Cancun," Figueres said.

"This week governments had to address together what was doable in Cancun. They have actually done that."

'Confidence in success'

She said she was confident a plan by rich nations to give developing countries $30b dollars to help them cope with climate change would be finalised at Cancun, helping build trust between the two sides.

"I have said and I will continue to say that fast-track finance is the golden key to Cancun. I am confident that the golden key will be dutifully unlocked," she said.

Delegates from more than 170 countries joined the latest round of long-running UN negotiations aimed at securing a binding global treaty on how to limit and cope with climate change.

The treaty would replace the Kyoto Protocol, which expires at the end of 2012, and aims to keep global warming below the threshold that scientists warn will trigger catastrophic damage to the world's climate system.

World leaders failed to broker such a treaty in Copenhagen last year as developed and developing nations battled over who should carry more of the burden in curbing greenhouse gases, which are blamed for global warming.