World powers plan to make Iran a "serious" offer of economic incentives at talks next week on its nuclear program, Western officials tell CNN.

In exchange for easing of sanctions barring trade with Iran in gold and other precious metals, the so-called P5+1 diplomatic bloc of countries wants Iran to shut its underground enrichment facility at Fordo, near the holy city of Qom and ship out its stockpile of uranium enriched to 20% purity, the officials said.

The group, comprised of Britain, China, France, Germany, Russia and the United States, plans to deliver the offer at talks next Tuesday in Almaty, Kazakhstan.

The offer presents a slightly revised package to the one presented to Iran last year during talks in Moscow, Baghdad and Istanbul, in which the group proposed fuel for a medical reactor and easing sanctions on aviation spare parts in exchange for Iran suspending its uranium enrichment and shipping its stockpiles out of the country.

"We couldn't come back with the same proposal," one official said. "But the idea is to test the waters and see where the Iranians are and if they are serious. We hope to get some insight into their thinking and see what they prioritize in their asks and offers."

Iran has defied international demands that it halt its production of enriched uranium, which it insists is to be used for civilian nuclear power and research reactors. But the United States and Israel have accused Iran of seeking the capability to produce nuclear weapons, and the International Atomic Energy Agency says it can no longer verify that Iran's nuclear program is strictly peaceful.

The new deal also takes into account the advances at the Fordo plant, asking Iran to permit wider IAEA inspections and to take steps that would make restarting Fordo a more difficult and time-consuming process.

"The logic of it, if the Iranians accept this, is that [the Iranians] have to erase the progress [they] made since the last talks," the official said.

Iran's refusal to shut down its uranium enrichment plants has led to tougher and tougher economic sanctions that have crippled its economy. An oil embargo and banking restrictions have crashed the Iranian currency, the rial. New U.S. sanctions imposed in January targeted a handful of companies and individuals that Washington says are providing materials and technology to Tehran's nuclear program.

Tehran has already rejected the new offer to be presented at next week's talks. But officials said they believe the deterioration of the Iranian economy may be causing the regime to consider making a deal.

Still, they acknowledged expectations of a major breakthrough are low for the Almaty talks, in large part due to skepticism that Iran's political leadership could make concessions ahead of the country's presidential elections in June.

Additionally, one Western diplomat said Iran may feel less pressure from the new Obama administration.

Both Secretary of State John Kerry and Chuck Hagel, President Barack Obama's nominee for defense secretary, have both been strong supporters of negotiations with Iran and are wary of any military action against Tehran's nuclear sites.

Both Kerry and Hagel have publicly supported having direct talks between Washington and Tehran, an idea proposed earlier this month by Vice President Joe Biden.

"More important than what we see from Iran is what we project," the diplomat said. "Many in the regime may think they have gotten past the worst part in terms of pressure. The best we can hope for in the short run is that we impress Iran with our steadfastness, and also show them we are ready to talk."