Japan plans to call for the U.N. Security Council to discuss imposing sanctions on Iran if Tehran does not promptly respond to the incentives package presented by six countries for resolving the nation's nuclear standoff, according to Japanese government sources.

Tokyo will make the proposal at the July 15-17 Group of Eight summit of major powers in St. Petersburg, Russia, the sources said, adding that if the Security Council reopens talks on the issue, adoption of a resolution paving the way for economic sanctions and other measures against Iran would draw renewed attention.

However, it remains uncertain if the G8 leaders will be able to reach a consensus on the need for Security Council talks because Russia, the host of this year's G8 summit, is reticent about adopting such a resolution, the sources said.