The United States seeks a balanced outcome in the Cancun climate negotiations that cover all major issues concerning climate change, U.S. Special Envoy for Climate Change Todd Stern said Friday.

"What we need to do is to produce a balanced package of decisions covering all the core issues from the Copenhagen Accord, including mitigation, transparency, financing, technology, adaptation and the REDD (Reducing Emissions from Deforestation and Forest Degradation) issue," Stern told a press conference.

An agreement that does not make comparable progress on all of them is not acceptable, Stern said.

"Anyone who says that any of these issues is too difficult or should be put off for another day is not trying hard enough," he said. "None of these issues is too difficult for us and none of them should be put off."

Stern said while differences still remained, a lot of useful works had already been done and he had seen some good ideas put on the table.

He said he was hopeful that negotiators could work through all differences, adding that balance was the key in Cancun.

"Balance is, in my judgment, the key that can unlock the door to a strong set of decisions here in Cancun," he said.

Stern's stance was not new. At a briefing on Nov. 22, he said "to preserve the balance of the package in Cancun, we need to make comparable progress on all the core issues included in the Accord."

Developing countries have accused developed countries including the United States of producing lots of carbon emissions and consuming too much energy over the past decades.

They demand the Cancun talks attach more importance to urging developed countries to share more burden in emissions cut and provide more fund and technology to developing countries.

The UN climate change conference, running from Nov. 29 to Dec. 10 in the Mexican resort of Cancun, aims to find solutions to global climate change.

Attendees include some 25,000 governmental officials, businessmen as well as members of nongovernmental organizations and research institutions from some 200 countries.