DURBAN - The UN climate conference currently under way in Durban, South Africa, should clearly establish the second commitment period under the Kyoto Protocol, the Chinese delegation said here on Monday.

The second commitment should ensure that developed country parties to the Kyoto Protocol "should undertake quantified emission reduction commitments," said Wei Su, deputy head of the Chinese delegation attending the COP 17, formally the 17th Conference of Parties to the United Nations' Framework Convention on Climate Change (UNFCCC).

Su was speaking on behalf of China, Brazil, South Africa and India, known as four "basic nations" in efforts to address climate change.

"The Kyoto Protocol is the cornerstone of the climate regime and its second commitment period is the essential priority for the success of Durban Conference," he said.

The pact, reached in 1997, requires 37 industrialized countries to slash carbon emissions to 5 percent below 1990 levels by 2012. But as the first commitment period is set to expire by the end of next year, the COP 17 is trying to ensure the protocol's continuation.

The United States, the world's largest polluter per capita, has said it would not sign up for an updated Kyoto Protocol. It wants the pact to impose obligations on emerging economies like China and India.

Europe says it can accept a continuation of the Kyoto Protocol, provided China and the United States show they are serious about major cuts in the coming years.

Japan, Canada and Russia, three key countries in the Kyoto deal, have made it clear that they will not sign up to a second commitment period.

The nearly irreconcilable differences leave the pact's future in doubt.

Referring to the differences, Su reiterated the support to work towards the perspective of a comprehensive, ambitious and fair outcome, ensuring the full, effective and sustained implementation of UNFCCC and its Kyoto Protocol.

He stressed that the continuation of the flexibility mechanisms of the Kyoto Protocol is contingent upon the establishment of quantified emissions reduction commitments by developed countries under the second commitment period.

"We re-iterate that it is hardly conceivable that a country would leave the Kyoto Protocol to do more. As the parties are working under the mandate of the Bali Roadmap to agree on a second commitment period under the Kyoto Protocol and to enable the full, effective and sustained implementation of the Convention through long-term cooperative action, now, up to and beyond 2012, we reaffirm the need to focus on this mandate."

He stressed that the continuation of the flexibility mechanisms of the Kyoto Protocol is contingent upon the establishment of quantified emissions reduction commitments by developed countries under the second commitment period.

"We are open to constructively engaging with Parties that are ready to enter the second commitment period," Su said.

He voiced hope that the Durban Conference should achieve "a comprehensive, fair and balanced outcome to enable the full, effective and sustained implementation of the Convention and its Kyoto Protocol, in accordance with the principles of equity and common but differentiated responsibilities and respective capabilities, and fulfilling the mandate of Bali Roadmap in the two-track process of negotiation."

"We emphasize the need to implement the Cancun decisions as well as to address the unresolved issues from the Bali Roadmap," he said.

"The Durban outcome should accomplish the Bali Action Plan where developed country parties that are not Parties to the Kyoto Protocol should undertake comparable quantified emission reduction commitments under the Convention and the developing country parties should implement enhanced mitigation actions in the context of sustainable development and enabled and supported by finance, technology and capacity building."

He also emphasized the need to address emissions from international aviation and maritime  transport in a multilateral context and in accordance with the principle of common but differentiated responsibilities and respective capabilities.