Sarkozy, Obama Call on Iran to Hold 'Serious' Nuclear Talks

French President Nicolas Sarkozy and U.S. President Barack Obama urged Iran on Thursday to take upcoming nuclear talks seriously and suspend sensitive atomic activities.

"They called on Iran to seize the opportunity of the resumption of talks with the Six (world powers) to engage in serious negotiations and suspend all sensitive nuclear activities," Sarkozy's office said in a statement after the two leaders held video-conference talks.

"The two presidents noted their determination to apply sanctions with the greatest firmness as long as Tehran refuses to meet its international obligations, in particular Security Council resolutions on its military nuclear program," the statement said.

World powers and Iran meet Saturday in Istanbul to discuss Tehran's promised "new initiatives" on its nuclear activities, after a 15-month break in talks.

The so-called P5+1 powers -- permanent U.N. Security Council members Britain, China, France, Russia and the United States plus Germany -- suspect Iran is concealing its real purpose of producing atomic weapons.

The powers want Iran to stop enriching uranium to 20 percent, ship out its existing stocks and open itself up to more intense inspections by the U.N. nuclear watchdog.

The last round of talks between Iran and the world powers was held in Istanbul in January 2011, but failed to produce results.