Stockholm  - UN Secretary General Ban Ki-moon on Saturday called the UN climate change conference in Copenhagen that opens in one month's time "a unique opportunity that should not be wasted."

"It is crucial that we achieve an ambitious climate agreement in Copenhagen," Ban wrote in an article penned exclusively for the Stockholm daily Svenska Dagbladet.

"The time is ripe. Climate change impacts other challenges we face. Global poverty and public health. Economic growth. Secure food supplies. Clean water. Energy," he said.

The UN head said he would "continue to push for an agreement that was as ambitious as possible, and a deal that was in line with fundamental scientific assessments and draws up the end goal for a legally binding global deal."

"All details don't have to be fixed in Copenhagen, but the meeting must result in a clear decision that establishes the basis for a global climate deal," Ban said, adding that "each country must contribute."

In addition to "ambitious" cuts of greenhouse gas emissions by developed countries and that developing countries "must do more to curb the increase in their emissions", governments "need to agree on a big financing and technology package to help developing countries reduce their emissions and tackle the effects of climate change."

A transparent system was also necessary, he said, noting that "these were minimum requirements" for a deal in Copenhagen to be called a "success."

"It is ultimately up to governments to decide on the content and form of an agreement," Ban concluded.

He lauded the 27-nation European Union for its mid-term emission targets and urged the bloc to "show an equally bold leadership in terms of climate financing."

Sweden is the current holder of the rotating EU presidency. The UN conference on climate change is set to take place in the Danish capital from December 7-18.(dpa)