A new negotiation text was tabled on Saturday halfway into the United Nation's two-week climate change negotiations, as environmental ministers from more than 190 countries arrived at Cancun to seek common ground for a package of climate solutions.

Heads of states and governments from more than 30 countries will also attend the Cancun climate talks, delivering their statements on national policies in reducing greenhouse gas (GHG) emissions.

Observers say the 33-page draft offers "cautious optimism" for progress, despite the fact that rich and poor nations remain at stark differences on the fate of the Kyoto Protocol - the only existing legally binding treaty to curb greenhouse gas emissions.

The Kyoto Protocol, adopted in 1997, set emissions reduction targets for industrialized countries between 2008 and 2012, known as the first commitment period. The United States is the only developed country that did not ratify the protocol. Nations are struggling to hammer out a new deal to cut emissions after 2012.

Su Wei, China's chief climate negotiator, told the conference that the second commitment period of the regime is "an indispensable element" of the final outcomes of the Cancun meeting.

"There is no compromise on the two-track negotiations, no compromise if the interests of developing countries are violated, and no compromise on the second commitment period of Kyoto Protocol," China's special climate envoy Huang Huikang said.

On the first day of the Cancun climate meeting, Japan bluntly announced it would refuse to sign up to a second commitment period. Notable countries - such as Canada and Mexico - have also signaled a desire to walk away from the Kyoto Protocol.

Their announcement has aroused serious concerns from most developing countries.

An Indian representative said at the conference on Saturday that signatory nations to the Kyoto Protocol already recognized "very specifically subsequent commitment periods."

Unfortunately, the second period of commitments by developed countries is now "under clouds, and a balanced outcome will be severely handicapped".

A Cuban delegate stressed that it is "a matter of urgency" for industrial nations to commit to the second round of the Kyoto Protocol.

Not only that this is a legal mandate, it is also "a legal obligation that must be met (for) a successful outcome in Cancun", the Cuban delegate said at the conference.

"Adoption of a second period of commitment under the Kyoto Protocol is the cornerstone to ensure a successful Cancun meeting."

Mexican Foreign Minister Patricia Espinosa, who also serves as the conference president, urged delegates to compromise, and said they had made progress on some areas in the first week. "I call upon you to act with a renewed sense of urgency," she said.

Su Wei also said it is urgent for all parties to speed up the pace of negotiation in the second week of the climate summit.

"Key questions remain unanswered and ministers have significant challenges ahead but a balanced package that makes progress on critical issues is within reach," said Tim Gore, climate change policy adviser for Oxfam, a UK-based non-governmental organization.

Jake Schmidt, the international climate policy director from the Nature Resource Defense Council said progress could be achieved in setting up a climate fund, technology transfer mechanisms and adaptation.

The transparency and accountability issue could also move forward as China has adopted a very active approach after the Tianjin climate meeting in October, he added.