Iran to resolve a protracted dispute over its atomic program will take place in January, Reuters reported citing Russian media.

The Russian agency quoted a foreign ministry spokesman as saying the world powers - the United States, Russia, France, Britain, Germany and China - were still negotiating with the Islamic Republic on a possible date and venue for the talks.

Iran is refining uranium to a fissile concentration of 20 percent, which Western experts say is a relatively short technical step from the level that would be required for bombs.

Iran says it needs higher-grade uranium to run its medical research reactor in Tehran.

"Currently negotiations are under way with Tehran on the place and date," the foreign ministry spokesman said.

"We hope that this work will be completed in the near future and such a meeting will take place in January of next year."

The last round of big power talks with Iran in Moscow in June ended with no sign of a breakthrough on tensions surrounding Tehran's nuclear ambitions.

The six powers want to rein in Tehran's uranium enrichment program, to ensure it is geared only for civilian energy, through a mix of diplomacy and sanctions. Iran denies Western assertions that it is seeking a nuclear weapons capability.