BAGHDAD — Diplomats from six world powers offered Iran new proposals Wednesday to ease international concerns about its nuclear program, but appeared to reject Tehran's appeals to ease economic sanctions to help move along talks.

The proposal by the U.S. and its negotiation partners focused on Iran's highest-level uranium enrichment — at 20 percent — which many world leaders fear could be quickly turned into warhead-grade material. Other details of the plan were not immediately disclosed.

But the proposal may meet a swift refusal from Iran. Its envoys seek agreements to lessen, or at least delay, sanctions that have targeted Iran's critical oil exports and cut off the country from lucrative European markets.

"We hope the package that we put on the table is attractive to them so they will react positively," Mike Mann, spokesman for the head of the European Union delegation that is leading the talks, told reporters. "It's up to them to react."

Mann would not discuss whether the 20 percent level enrichment represented a red line that could again scuttle the negotiations, which had only restarted last month after collapsing in early 2011.

The high-enriched uranium is far above the level needed for energy-producing reactors, but is used in medical research. Iran claims its nuclear program is only for electricity and medical applications.

Tehran has tentatively agreed to allow U.N. inspectors to restart probes into a military base with suspected links to nuclear arms-related tests. Mann expressed cautious optimism about the still-unsigned deal with the International Atomic Energy Agency, but said it would have little bearing on Wednesday's talks.

Despite the new proposals, no breakthrough accords are expected in the talks in Iraq's capital, suggesting that all sides are still shaping their strategies and the negotiation process is likely to be long.

That could allow U.S. and European allies to significantly tone down threats of military action. But it would likely bring objections from Israel, which claims that Iran is only trying to buy time to keep its nuclear fuel labs in full operation.

Mann suggested that any rollback in sanctions was unlikely in the Baghdad talks. He said some of the most painful sanctions — including a European Union ban on Iranian oil imports beginning July 1 — are a "matter of the law and they will come into force when they come into force."

The Obama administration has been vague about its immediate goals, with officials saying the talks will gauge Iran's seriousness and explore elements of a possible agreement. A Western diplomat in Baghdad said the talks will focus on "confidence-building measures" that Iran's nuclear program is only being used for peaceful purposes.

"This approach includes concrete step-by-step, reciprocal measures aimed at near-term action," the Western diplomat said, speaking on condition of anonymity to discuss the delicate process more candidly.

Washington has shown little willingness to bargain, despite the tentative IAEA agreement to inspect the Parchin military complex southeast of Tehran. That's where the U.N. believes Iran ran explosive tests in 2003 needed to set off a nuclear charge. Tehran says Parchin is not a nuclear site.

Iran's top officials, including Supreme Leader Ayatollah Ali Khamenei, have repeated said that Iran does not seek nuclear arms and have called such weapons against Islamic principles.

During a visit to western Iran on Wednesday, President Mahmoud Ahmadinejad evoked Khamenei's belief that "production and use of weapons of mass destruction is forbidden" by Islam.

"There is no room for these weapons in Iran's defense doctrine," he said at a gathering to commemorate victims of Iraqi chemical weapons during the 1980-88 war with Saddam Hussein's Iraq.

He claimed a "WMD-free world is honest and wish of the Islamic republic."

Iranian analyst Hassan Abedini, who is being briefed by Iran's delegation, said Tehran expects the U.S and other world powers to offer some concessions in return for the tentative agreement with the U.N.'s nuclear agency.

"Now the ball is in the (world powers') court to reciprocate it," Abedini said Wednesday.

He said Iran is demanding "a give-and-take approach," to the negotiations.

The Baghdad talks, involving the five permanent U.N. Security Council members plus Germany, could offer a test of how much the U.S. and allies are willing to bend from demands for Iran to halt all uranium enrichment and instead concentrate on just stopping the highest-grade production.

Iran is sticking to its right to enrich uranium as a signatory of U.N. nuclear treaties. The West and others fear the level of enrichment Iran is doing can be turned quickly into weapons-grade uranium.

At the heart of the debate are sanctions the West has placed on Iran to force it to the bargaining table — particularly on a European Union decision to cut all crude oil imports from Iran that are set to take effect July 1. The 27-nation EU accounts for just 18 percent of Iran's total oil exports.

Earlier this week, the U.S. Senate backed proposals for further sanctions on Iran, including requiring companies listed on U.S. stock exchanges to disclose any Iran-related business. U.S. and European measures already have targeted Iran's oil exports — its chief revenue source — and effectively blocked the country from international banking networks.

Oil fell to a seven-month low near $91 a barrel Wednesday in Asia on hopes of progress in the talks.

Associated Press writers Brian Murphy in Dubai, United Arab Emirates, and Nasser Karimi in Tehran, Iran, contributed to this report.