Germany's chancellor, Angela Merkel, second from right, talks with French President Nikolas Sarkozy, far left, during the UN climate summit in Copenhagen on Dec. 17. (Heribert Proepper/Associated Press)

With the Copenhagen climate change conference into its second-last day, world leaders staged a late push on Thursday to reach an elusive deal.

"In these few days in Copenhagen, which will be blessed or blamed for generations to come, we cannot permit the politics of narrow self-interest to prevent a policy for human survival," U.K. Prime Minister Gordon Brown said in an address to the conference.

For all nations, "there is no greater national interest than the common future of this planet," he said.

Canadian Prime Minister Stephen Harper arrived in Copenhagen on Thursday, joining the leaders of the 192 countries attending the summit.

Prime Minister Stephen Harper arrives in Copenhagen for the 2009 United Nations conference on climate change on Dec. 17. (Sean Kilpatrick/Canadian Press)

However, he is expected to maintain a relatively low profile, as he is not due to speak at the conference. He is slated to leave Friday as soon as the summit is over.

Environment Minister Jim Prentice said in Copenhagen that the key issue from Canada's perspective is that of measurable and verifiable emissions, specifically from China, India and Brazil.

"We're quite prepared to have Canadian emissions and Canadian reductions subject to full transparency and full international scrutiny," he told reporters.

U.S. Secretary of State Hillary Rodham Clinton said during a news conference that her government is prepared to join other rich nations to back $100 billion US in annual support by 2020 for poorer countries to grapple with climate change.

The U.S. backing could give a boost to the talks, which are nearing the end of their two-week run.

The talks have been marked by disagreements between rich and developing countries about emissions targets and financing.

'Kind of a deal breaker for us'

Disagreement between the U.S. and China has become one of the sticking points at the summit. While China is promising to cut the growth of its greenhouse gases, the U.S. wants China to submit to international verification to prove it's living up to its commitments — something that China said it won't support.

If there is no verification, there won't be a deal, said Clinton.

"If there is not even a commitment to pursue transparency, that's kind of a deal breaker for us," she said.

China later indicated it is willing to meet the United States part way on its demands.

Beijing is ready for "dialogue and co-operation that is not intrusive, that does not infringe on China's sovereignty," said Chinese Vice-Foreign Minister He Yafei.

While Clinton and Brown sounded optimistic tones during their speeches, not everyone shared their view.

One Danish official, who spoke on condition of anonymity, said a deal appeared unlikely.

"As it looks now, we will not get the deal that we had hoped for," said the official.

With files from The Associated Press