In return, Tehran is expected to ask Washington and the European Union to start scaling back sanctions that have frozen the country out of much of the international financial system and isolated its oil industry, the officials told The Wall Street Journal ahead of a new round of talks in Geneva, Switzerland, with the so-called P5-plus-1 group starting Tuesday.
The P5-plus-1 powers are the five permanent U.N. Security Council members -- the United States, Britain, China, France and Russia -- plus Germany.
"The Iranians are preparing to go to Geneva with a serious package," a former Western diplomat who has discussed the incentives with senior Iranian diplomats told the Journal.
"These include limits on the numbers of centrifuges operating, enrichment amounts and the need for verification," the former diplomat said.
On that last point, Iran is expected to offer to open the country's nuclear facilities to more expansive international inspections, the former diplomat and U.S. and Middle East officials told the newspaper.
Tehran is also considering the possibility of offering to close Iran's deep-underground Fordo uranium-enrichment plant south of Tehran, near the holy city of Qom, although a final decision hasn't been made, the Journal said.
Washington and Jerusalem allege the Fordo plant -- Iran's most heavily armed and protected nuclear site, controlled by the country's elite Islamic Revolutionary Guard Corps -- is part of a covert Iranian weapons program. Tehran denies this and insists its entire nuclear program is simply developing civilian nuclear power.
Iran's initial proposal is expected to include an offer to stop enriching uranium to levels of 20 percent purity, which international powers consider dangerously close to a weapons-grade capability, the Journal said.
The P5-plus-1 offered sanctions relief in February if Tehran agreed to suspend its 20 percent enrichment, remove most of its stockpile of already produced 20 percent enriched uranium and stop activities at Fordo.
Iranian President Hassan Rouhani and Foreign Minister Javad Zarif have said in recent weeks Tehran will not suspend all of its nuclear-fuel production, which includes uranium enrichment to levels between 3 percent and 5 percent purity.
These levels are usable for power reactors but not for weapons.
Prime Minister Binyamin Netanyahu told the U.N. General Assembly last week Israel wouldn't accept Iran having the ability to enrich uranium at any level. He said Jerusalem was concerned this would let Tehran maintain the latent ability to produce weapons-grade fuel.
Iranian Parliament Speaker Ali Larijani said Tuesday Tehran could prove it's not developing nuclear weapons.
"From Iran's side, I can say that we are ready," Larijani told CNN from Geneva.
"If the Americans and other countries say that Iran should not develop a nuclear bomb or should not move toward that, then we can clearly show and prove that," he said.
"We have no such intention. So it can be resolved in a very short period of time."
But he said the West must accept Iran's right to enrich nuclear fuel for peaceful civilian purposes. Such use of nuclear fuel is permitted under the Treaty on the Non-Proliferation of Nuclear Weapons, or Non-Proliferation Treaty, which Iran signed.
"If they want to bargain with us or if they have ulterior motives -- or maybe they want to somehow convince Iran to abandon its nuclear program -- then it is going to take a long time," Larijani said.
Senior Obama administration officials have refused to say if Washington would accept Tehran's maintaining the ability to enrich uranium at the lower levels.
"I'm not going to negotiate in public," Undersecretary of State Wendy Sherman, the Obama administration's chief Iran negotiator, told a Senate hearing last week. "All I can do is repeat what the president of the United States has said: We respect the right of the Iranian people to access peaceful nuclear energy."
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