Developed nations are trying to wriggle out of legal targets to curb global warming, Chinese chief negotiator Su Wei told AFP.
"They try to evade the legally binding commitments," he said on the sidelines of negotiations in the former German capital Bonn.
On Wednesday, the European Union warned that the effort to forge a new global pact on climate change by 2015 was in danger of floundering, and some negotiators pointed the finger at China.
"It is very dirty communication politics," Su said sharply, insisting his country has "shown a lot of flexibility."
European participants said China was blocking attempts to launch a negotiating track, set up only six months ago at talks under the UN banner in Durban, South Africa.
Known by the initials ADP -- for ad-hoc talks on the "Durban Platform" -- the track is supposed to draft a new climate pact by 2015 binding all nations, rich and poor, to take effect by 2020.
But the arena has been badly troubled since the Bonn talks began on May 14, and only a few hours remain on Friday for resolving big organisational problems and appointing officials.
Su named the United States, Europe, Japan, Canada, Australia and New Zealand as among countries abusing the Durban Platform "to jump from the legally binding system" established under the UN Framework Convention on Climate Change (UNFCCC).
"They try to evade the legally binding commitments under the KP and the LCA," he said, referring to the Kyoto Protocol and so-called Long-term Cooperative Action.
Under the Kyoto Protocol, whose first leg ends this year, 37 industrial countries are held to specific goals for slashing emissions of Earth-warming greenhouse gases. Poorer countries have no binding targets.
The LCA is a process under which the 195 parties of the UNFCCC target a two-degree-Celsius (3.6-degree-Fahrenheit) global warming limit.
"They are using the Durban Platform as a scapegoat for them to have no legally binding commitments because the Durban discussions... are not legally binding," said Su of the rich countries.
On Wednesday, Danish chief negotiator Christian Pilgaard Zinglersen warned about the state of the talks.
"If this slow pace of negotiations continues... it poses the risk of unraveling the Durban package," he said, speaking for the EU.
French climate ambassador Serge Lepeltier said that China specifically "gives the impression of having hardened its positions since Durban."
China is by far the world's number one carbon emitter and its 1.3 billion people are swiftly getting wealthier, which causes the country to burn ever more coal, gas and oil.
But it is also arguing fiercely for the 20-year-old UNFCCC principle that developing countries should not be asked to shoulder the same burden as rich economies for tackling the greenhouse-gas problem.
Environmental groups added their voice to the row.
"We are very concerned that the blame game has started to blame the developing countries like China for blocking. What we see is that the countries who are actually blocking are the northern parties, the developed countries," said Meena Raman of the Third World Network.
"When developing countries try and focus on the heart of the matter, on how we are to deal with emission cuts in a principled way, they get accused of 'procedural blocking'," added Mithika Mwenda of the Pan African Climate Justice Alliance.
"To us Africans, facing the deadly droughts and changing rainfall patterns, what is blocking this process is the US refusing to negotiate its emission target at all. Blocking is the European Union offering a business-as-usual 20-percent target while allowing weak accounting rules in the Kyoto Protocol."
Canada meanwhile insisted it remained "committed" to fighting global warming despite last year becoming the first country to quit Kyoto.
"We came here to confirm our willingness to start negotiations on a new accord as soon as possible," chief negotiator Guy Saint-Jacques told AFP.
Earlier this month, Canada said it would not reach its aim of reducing greenhouse gases by 17 percent from 2005 levels by 2020.