Speaking on the sidelines of talks in the Thai capital, Yu Qingtai, China's special envoy for climate change, said some nations needed to do some "deep soul-searching".
"What is happening right now in these negotiations is not very encouraging to say the least," Yu said, repeating a fear he expressed on Monday that some nations were trying to "terminate" the Kyoto Protocol, the UN's top weapon to curb climate change.
"Are we serious about the commitments that we undertake? Are we serious about the agreements that we reach? Do we have the political will to act on the basis on what we say?"
Yu said Annex 1, or rich, nations seemed to be shifting their positions to meet the stance of the United States. Washington wants any steps to cut emissions to be effective under domestic law but has been ambiguous on whether any new climate pact from 2013 should be internationally binding.
The United States never ratified Kyoto, which binds 37 industrialised nations to emissions targets during its first commitment period from 2008 to 2012.
"What we see now is the move, the other Annex 1 countries, moving to what the US is prepared to put on the table, to make it comparable. So what is happening right now is not very encouraging."
The shape of a post-2012 climate agreement is a key focus for delegates from about 180 nations meeting in Bangkok. Officials are trying to bridge differences over a draft negotiating text that will allow all countries to deepen efforts to slow the pace of climate change.
Key to that issue is rich nations toughening their commitments to cut emissions from 2013.
Developing nations, including China, say rich countries are historically responsible for most of mankind's greenhouse gas pollution in the atmosphere since the Industrial Revolution and that they have the right to expand their economies to help fight poverty.
Many developing nations want industrialised countries to cut emissions by at least 40% below 1990 levels by 2020. Current pledges are far below that.
Lack of action brings disappointment
Yu said China was disappointed rich nations were trying to dishonour what was agreed in major climate talks in Bali in 2007.
Those talks set a two-year deadline to agree on a new climate framework and formalised two negotiating tracks. One of those tracks would focus on emissions reduction commitments during a second commitment period from 2013.
"Everybody agreed in Bali that there should be a twin-track system and one of the tracks should be a discussion of the second commitment period. But now people are trying to take away the wheels on this track," Yu said.
"At the same time they are working to terminate the Kyoto Protocol before the second commitment period gets under way. So there is a contradiction here."
The Bali talks also crafted a clause just for the United States that recognised all industrialised countries had to take action to cut greenhouse gas emissions and that these efforts should be comparable.
Yu said the US commitments should be comparable to the European Union, Canada and other rich nations.
"We are prepared to negotiate with everybody what comparability should mean. In our view it should be comparable in terms of magnitude, in terms of legal nature, it should be a set of commitments rather than national actions, which is meant for developing countries."
(EurActiv with Reuters.)