He said his visit showed China was "willing to join hands with the international community to face this global challenge, with the utmost sincerity and determination."

in depth

China is the world's second-biggest carbon emitter after the US and is a key player in influencing developing world support for any deal on emissions cuts.

Negotiators in Copenhagen have just two days left to broker a new pact before a Friday deadline, but days of bitter wrangling between key players have prompted warnings that the deadlock will not be broken.

Wen himself is due to elaborate on China's position on climate change in a speech to the summit.

"I hope that the summit will yield a fair, reasonable, balanced and achievable result through the joint efforts of all parties," the Chinese premier said according to the foreign ministry a statement.

'Hopeful'

Speaking ahead of Thursday's penultimate talks session, the deputy-head of the Chinese delegation, Su Wei, said he was hopeful a positive outcome could be reached by the end of the conference.

Wen is set to lay out China's position in a speech to the climate summit [EPA]
However, an official close to the talks was quoted by the Reuters news agency early on Thursday as saying the Chinese delegation had all but ruled out reaching an operational accord.

The official, speaking on condition of anonymity, said the Chinese had suggested instead issuing "a short political declaration of some sort", although it was not clear what that would say.

Speaking to Al Jazeera, Victor Gao, director of a Chinese government-affiliated think-tank the China National Association of International Studies, said he doubted that Chinese officials had written-off hope of reaching a deal.

The negotiations had been difficult and challenging, Gao said, "but I don't think the Chinese premier would go to Copenhagen without planning to commit our country to this global accord."

China has vowed to reduce carbon emissions per unit of gross domestic product by 40 to 45 percent by 2020.

But given the country's economic growth projections, but experts say its emissions could still double under those standards.

Beijing has long argued that developed nations should carry the bulk of the cost of emissions cuts as well as provide financial and technical help to poor countries battling climate change.