The talks among the U.N. Security Council's five permanent members and Germany may expose differences within the group, as the United States pushes for more sanctions while China has made clear that it does not think the time was ripe.
The United States accuses Iran of using its civil nuclear program as a cover to pursue an atomic bomb and has led the push for more punitive measures within the Security Council, which has already passed three rounds of sanctions on Tehran.
Iran, which has seen its most serious domestic unrest since the 1979 Islamic revolution in street protests over a disputed June election, says its nuclear program is to produce power so that it can export more of its valuable oil and gas.
Secretary of State Hillary Clinton said last week the United States had begun talks with like-minded nations about sanctions they might impose on Iran's government and Revolutionary Guards without hurting ordinary Iranians.
Saturday's meeting will bring together Britain, China, France, Russia and the United States as well as Germany.
Clinton told reporters Washington was weighing "what would have the biggest impact, of perhaps changing the strategic calculation inside Iran of the current leadership."
"There is a relatively small group of decision makers inside Iran. They are in both political and commercial relationships. And if we can create a sanctions track that targets those who actually make decisions, we think that is a smarter way to do sanctions," she said. "But that is all to be decided."
Clinton, told reporters as she flew to Hawaii at the start of a trip to Australia, New Zealand and Papua New Guinea, the Iran meeting would take place later this week in New York. Other diplomats said it was slated for Saturday.
WILL CHINA "STOP THE TRAIN?"
Iran has effectively rebuffed the West's year-end deadline to accept an nuclear fuel deal aimed at quelling international fears it is trying to build nuclear arms.
Under the deal, Iran would transfer stocks of low-enriched uranium abroad and in return receive fuel for a medical research reactor. The deal aimed to minimize the risk of Iran refining the material to a grade suitable for a weapon.
Asked about suggestions Iran may have floated a new nuclear proposal, Clinton said: "We get a constant flow of feelers from the Iranians on approaches that they might consider."
Diplomats said Iran's unwillingness to go through with the deal appeared to have prompted Russia to consider more sanctions. But China, which is averse to sanctioning other nations, is a different matter.
China's U.N. ambassador last week doused Western hopes for a swift agreement on a fourth round of U.N. sanctions against Iran, saying the issue requires more "time and patience."
"The Chinese have an established point of view on sanctions but ... are they prepared to stand up and stop the train?" said a U.S. official, who spoke on condition of anonymity. "We have a strong belief that the answer will be no -- that they won't stop the train, that they don't want to be isolated."
Another diplomat, however, questioned whether China -- having acquiesced in previous three U.N. sanctions resolutions -- may now be taking a more muscular stance to oppose further punitive measures on Iran.
