The weak accord with which the United Nations climate summit closed is a harbinger of world leaders' likely future failure in efforts to impose tougher sanctions against Iran, diplomats said Saturday.

The historic climate talks ended Saturday after a 31-hour negotiating marathon, with delegates accepting a U.S.-brokered compromise that gives billions in climate aid to poor nations but does not require the world's major polluters to make deeper cuts in their greenhouse gas emissions.

Following the end of the summit, diplomats said that China's flexing of its political muscles in its disputes with the United States at the conference should serve as a warning of what will happen when the Obama administration seeks to bring tougher sanctions against Iran for UN Security Council approval.

The diplomats, who were referring to the dispute over Iran's nuclear ambitions, spoke on the condition of anonymity.

The Obama administration has said that time is running out for the diplomatic approach to resolving the crisis, and six world powers are expected to consult by telephone on December 22, and are considering a fourth round of UN sanctions against Tehran come January.

Earlier Saturday, Iranian Foreign Minister Manouchehr Mottaki said that Tehran was ready to consider a recent proposal issued by Western nations under which Iran would obtain nuclear fuel from outside sources rather than producing it itself, the official IRNA news agency reported.