Obama and Sarkozy "discussed the need to continue a unified international approach to address Iran's nuclear ambitions," a White House statement said.

The leaders "expressed the hope that the resumption of dialogue (with Iran) would result in decisive progress in coming weeks in accordance with Iran's international obligations and noted that Iranian cooperation would be evaluated by the end of the year," a statement from the Elysee palace said.

The call also involved discussion on climate change, ahead of a December conference in Copenhagen to draw up an international climate agreement to replace the Kyoto Protocol, which expires in 2013.

"The two presidents agreed to increase cooperation between France, the European Union and the United States, to contribute to the success of the Copenhagen summit," Sarkozy's office said.

Iran's nuclear program has been a top international priority because of fears it masks development of a nuclear weapons. Tehran says the program is for peaceful civilian energy.

On October 1 in Geneva, representatives from Iran and a group of international powers agreed that Tehran would allow inspectors to visit a newly-revealed uranium enrichment site near Qom, in the center of Iran.

The talks are set to restart on October 19 in Vienna and will focus on a proposal to enrich Iranian uranium in a third country.

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