U.S. Secretary of State Hillary Rodham Clinton said Tuesday that recent talks between the International Atomic Energy Agency (IAEA) and Iran have no obvious progress over the Islamic republic's nuclear program, adding that the United States would continue working with partners on tough sanctions.

"Iran's continued disregard for its international obligations underscores the importance of united international pressure to change its policies. The United States is working with our partners on tough new sanctions that will further sharpen the choices that Iran's leaders face," the secretary told reporters after meeting with European diplomats.

Iranian Foreign Minister Manouchehr Mottaki last met with IAEA Director General Yukiya Amano in Vienna, and discussed the plan brokered by the international watchdog last October under which Iran's low-enriched uranium was to be exported to Russia for further enrichment and then to France for processing into fuel for Iran's nuclear reactor.

"My personal opinion is that there is a more serious willingness to follow up the uranium exchange case and I am confident that the deal could still be realized if there was genuine political will," said the foreign minister after his visit to the IAEA.

The United States, Israel and other Western countries voice deep concerns on Iran's nuclear program, saying Tehran may obtain the uranium fuel needed for nuclear weapons by the same process to purify uranium. Iran insists its nuclear program is for peaceful purpose.

The Obama administration has been trying to push the fourth round of sanctions on Iran under the framework of the United Nations, in an attempt to make Iranian leaders realize the "importance of changing their actions and decisions concerning their nuclear program."