Iranian officials have agreed to meet Tuesday with a senior EU representative delivering a six-nation package of rewards and penalties meant to stop Tehran's uranium enrichment program, diplomats said.

Iran's Supreme Leader Ayatollah Ali Khamenei waves before speaking in Tehran, June 4, 2006. [Reuters]

Javier Solana, chief European Union foreign policy official, had been expected to present the proposal to Iranian officials sometime this week, but the precise day had not been divulged. The diplomats, who spoke on condition of anonymity because the timetable was confidential, said Monday that Solana would submit the package to Foreign Minister Manouchehr Mottaki the following day.

The package put together by the United States, Russia, China, Britain, France and Germany dangles the promise of economic and political incentives if Tehran relinquishes domestic enrichment, which can generate power as well as make weapons-grade uranium for warheads. It also contains the threat of U.N. sanctions if Iran remains defiant.

In a breakthrough last week, the United States agreed to join in multinational talks on the package if Tehran suspends enrichment.

Diplomats said Monday that Washington has sweetened the offer by saying it will lift some bilateral sanctions on Tehran such as a ban on Boeing passenger aircraft and related parts if Iran agrees to an enrichment freeze.

Iranian officials have sent conflicting signals on the six-nation initiative, reflecting a possible struggle within the leadership on how to react.

Iranian President Mahmoud Ahmadinejad, normally a hardline critic of the United States who insists that Tehran has a right to enrichment, said on the weekend that a breakthrough in negotiations was possible and welcomed the U.S. offer to join talks, while rejecting preconditions.