The progress on climate talks in China has been slow and patchy according to an EU official.
There has been insufficient progress in translating key elements of the Copenhagen Accord into UN texts, Bloomberg quoted EU Climate Commissioner Connie Hedegaard saying.
"The lack of progress on these issues, and signs of backtracking on the Copenhagen Accord by certain parties, gives us cause for concern about the balance of the Cancun package," Hedegaard said.
But some progress on adaptation to climate change, climate finance and technology cooperation had been made in the country, the EU added.
The United Nations conference, which Hedegaard hopes to have more positive outcomes, is scheduled in Cancun, Mexico, and starts on 29 November this year.