BEIJING - The global climate change talks in Durban got off to a rocky start, with developed and developing countries holding diverging positions, indicating tough negotiations ahead.

The fate of the Kyoto Protocol, the sole international agreement that obligates industrialized countries to slash carbon emissions, remains the essential issue of the summit.

Developing countries are calling for an extension of the first commitment period which expires in December 2012.

"It is hardly conceivable that a country would leave the Kyoto Protocol to do more," said Su Wei, China's top climate change negotiator.

He reiterated that the Kyoto Protocol is the cornerstone of the climate regime and its second commitment period is the essential priority for the success of the Durban conference.

The Durban conference should clearly establish the second commitment period under the Kyoto Protocol where developed countries shall undertake quantified emission reduction commitments, he said.

"We cannot lower the bar for negotiations in Durban neither keep shifting goal posts," said Ambassador Silvia Merega of Argentina, on behalf of the Group of 77 developing countries and China.

"Durban should not be the burial ground for the Kyoto Protocol, rather, it should be the birthplace of the second commitment period."

"It must be preserved and strengthened if we are to ensure any meaningful multilateral response to the issue of climate change," she said.

Christiana Figueres, the UN's top climate official, said the protocol's future is "the defining issue of this conference".

She said an extension of Kyoto targets is linked to pledges that developing countries must make to join the fight against climate change.

The Canadian government was reported to be planning to pull out of the Kyoto Protocol after the Durban conference, indicating that it will not commit to new targets under the Kyoto Protocol after its first commitment period expires in 2012.

Meanwhile, the International Chamber of Shipping (ICS), which represents more than 80 percent of the world's merchant fleet, joined two non-governmental organizations, Oxfam and WWF, to propose a global levy on carbon emissions from merchant ships under a deal that would also channel proceeds to developing countries.

Maritime transport accounts for roughly 3 percent of world emissions of greenhouse gases.

But, like the aviation industry, it does not have any targeted curbs on this pollution.

In a joint statement, the ICS, WWF and Oxfam said carbon emissions from merchant ships could be subjected to "market-based measures" as an incentive to reduce greenhouse gases.

Part of the revenue from this could go to a planned Green Climate Fund that, in theory, will provide up to $100 billion a year for developing countries most at risk from climate change.

"If governments decide that shipping should contribute to the Green Climate Fund, the industry can probably support this in principle," ICS Secretary-General Peter Hinchliffe said in a statement.

"It is vital that governments meeting this month at the UN climate talks in Durban give the signal needed to move such a deal forward in the International Maritime Organization," Tim Gore, Oxfam climate change policy adviser, said in a statement.

Su said it's a necessity to address emissions from international aviation and maritime transport in accordance with the principle of common but differentiated responsibilities and respective capabilities.

Reuters and AFP contributed to the story.