Updated

Iran's (search) president said Monday that Tehran has given a set of proposals to three key European states involved in talks on Iran's nuclear program, which he stressed must be expanded to provide his country with more energy.

Mohammad Khatami's (search) remarks came a day after Iranian officials described progress on nuclear talks with Europe as unsatisfactory and too slow, while Iran's chief negotiator warned it soon may walk away from the discussions.

Europe is seeking Iranian guarantees that it will not use its nuclear technology to build bombs, something which the United States claims Tehran (search) is determined to do. But Iran says its nuclear program is aimed at producing energy.

"We have presented five proposals to Europeans, now it's their turn to provide us strong guarantee about security," Khatami was quoted by state-run TV during a visit to Iran's atomic energy organization to oversee a ceremony launching a new postage stamp lauding Iran's achievements.

Khatami did not elaborate, but the handover of the Iranian proposals indicates Tehran's willingness to continue the protracted discussions with the Europeans.

Talks between Iran and Britain, Germany and France, who negotiate on behalf of the European Union, ended without result last week. The two sides were to meet again March 23. The Europeans have been offering economic incentives for Iran to give up any weapons ambitions.

Khatami said Iran needs nuclear fuel to meet demands for more nuclear power plants.

"We need to build nuclear power plants; we have to be sure about their fuel supply," he said. "If we stop fuel production, what guarantees that they (European) could provide us with the fuel?"

It was unclear if Khatami was suggesting Iran could suspend its nuclear enrichment program if granted fuel alternatives by the Europeans.

Khatami said there is domestic opposition against dismantling Iran's nuclear program in line with U.S.-led demands.

Iran suspended uranium enrichment-related activities last year to create confidence in its negotiations and avoid U.N. Security Council referral for possible sanctions. Tehran says maintaining the voluntary freeze depends on progress in the talks with the Europeans.

On Saturday, Iranian Foreign Ministry spokesman Hamid Reza Asefi rejected U.S. overtures aimed at coaxing Tehran to drop its nuclear ambitions. The policy shifts, announced earlier by Secretary of State Condoleezza Rice, include dropping opposition to Iran's application for membership in the World Trade Organization and allowing the sale of some spare parts for civilian aircraft.

Rice signaled that Iran should quickly accept, or face the threat of sanctions.