An international agreement on climate change will be "really, really difficult but not impossible" to reach, says COP15 President Lars L?kke Rasmussen.

"Instead of making one agreement with two purposes, it is now necessary to make two agreements with one purpose. It's a more complicated process," said the president, who is also Denmark's Prime Minister.

The two agreement texts are respectively, a continuation of the Kyoto protocol and a broader cooperation in the so-called conference track, which is not legally binding.

L?kke Rasmussen hint that the negotiations could end successfully after all. Each day this week at the conference, the divide between developing and developed countries seems to have widened. But optimism has to a degree returned to the halls of the Bella Center, the conference venue.

Environment ministers, after taking over from the lower-level negotiators, reached the concluding hours of talks on the second-to-last day of talks, hoping to produce partially agreed upon deals to present to Chinese Premier Wen Jiabao, US President Barack Obama and the 110-odd world leaders on the last day of the summit.