UN Secretary-general Ban Ki- moon on Tuesday voiced optimism for a successful international conference in Copenhagen, saying that the gathering can be a "turning point" in the fight against climate change.

"I am encouraged and I am optimistic. I expect the robust agreement of the Copenhagen summit meeting will be effective immediately and include specific recommendations on mitigation, adaptation, finance and technology," Ban told reporters at the UN Headquarters in New York.

Such an agreement will have "an immediate operational effect as soon as it is agreed," he stressed, saying that the summit "can and must be the turning point" in the world's efforts to prevent climate change and "usher in a new era of green growth for all."

"From all corners of the globe, we see unprecedented momentum for a deal," said the secretary-general, who has announced that he will travel to Copenhagen for the upcoming high-level segment of the UN climate change conference.

More than 100 heads of state and government, including those from the United States, China and India, have said they will go to Copenhagen to provide their support for a global agreement, Ban noted.

"Never have so many different nations of all size and economic status made so many foreign pledges together," he said. "We must seize this moment and continue pushing for still higher ambition."

"We are united in purpose and now is the time for action. United in action and results," he added.

The secretary-general, who has made climate change a top priority since taking office in 2007, will be traveling to Copenhagen next week to attend the high-level segment of the summit which begins on Dec. 17.