South African President Jacob Zuma downplayed expectations Monday for the UN climate talks that kick off in his country next month and could decide the future of the Kyoto Protocol.

"We go to Durban with no illusion at all that it will be a walk in the park. On the contrary, we are fully aware that in some areas the national interest of parties will make consensus a challenge," Zuma told a meeting of the Socialist International movement in Johannesburg.

"Any outcome in Durban has to be adequate enough to adhere to the principle of environmental integrity. In this context the low level of ambition is a serious concern."

The Kyoto Protocol's current set of curbs on greenhouse gases expires at the end of 2012.

Officials are calling Durban a make-or-break meeting for the future of the agreement, the only deal to date with legally binding commitments to cut the carbon emissions that scientists say spell disaster for the planet's health if left unchecked.

Zuma praised climate negotiators for a "positive spirit for compromise" at preparatory talks earlier this month in Panama.

But he said the Durban talks, to be held from November 28 to December 9, will be successful only if they resolve the future of the Kyoto Protocol, reach agreement on the legal nature of future climate regulations, and "operationalise" agreements reached during the last round of talks in Cancun.