Setting a target of zero carbon emissions by 2050 is not "realistic," Saudi Arabia's chief negotiator at UN talks for a new, world climate pact said in Lima Monday.

"The zero-emissions concept -- or let's knock out fossils fuels out of the picture without clear technology diffusion and solid international cooperation programs -- does not help the process," the oil giant's envoy, Khalid Abuleif, told journalists on the sidelines of the talks.

"I do not think this is realistic when two billion people do not have access to energy."

Nations are gathered in the Peruvian capital to draft the outlines of a pact to curb potentially disastrous global warming by slashing greenhouse gas emissions from fossil fuels like coal, oil and gas.

The zero-emissions target is one option proposed in a draft negotiating document.

"When you say zero emissions without advancing carbon capture utilization and storage technology, you are sending a signal that is not really beneficial to the process," insisted Abuleif.

Setting such a target would be "very challenging to the future sustainable development of oil exporters," he said, adding any deal had to be "realistic and pragmatic."

Nations gathered in Lima are deeply divided on sharing out responsibility for carbon curbs, which requires a costly shift from cheap and abundant fossil fuels to less polluting energy sources.

Developing countries want rich nations to bear a bigger share of the burden, given their longer history of pollution and superior technology and resources.

But developed nations like the United States and Australia point the finger at major developing emitters that rely heavily on fossil fuel to power their rapid growth.

Saudi Arabia pumps about 9.7 million barrels of oil per day.

Last week, Standard and Poor's lowered the outlook for the world's top oil exporter to stable from positive on sliding oil prices, after the nation slashed the price of crude its sells to Asia and the United States in what analysts said was a bid for more market share.