The United States supports a proposal of the United Nations nuclear watchdog for Iran to process low-enriched uranium (LEU) in Russia and France, a U.S. State Department spokesperson said.

"We fully support the IAEA proposal to have this low-enriched uranium processed in Russia and France," Ian Kelly told a daily press briefing in Washington.

Delegations from Iran, the United States, France and Russia met on Monday in Vienna to discuss ways to resolve the controversial Iranian nuclear program and agreed to continue negotiations on Tuesday.

Mohamed ElBaradei, the head of the International Atomic Energy Agency (IAEA), positively assessed on Monday the start of the talks in the capital of Austria.

The talks were convened to discuss proposals for France and Russia to enrich uranium for Iran, to ease international suspicions of a covert Iranian atomic weapons program. Iran already produces low-enriched uranium (up to the 5% level), but says it wants to buy higher-enriched fuel (up to 20%) for a research reactor in Tehran, used for medical purposes.

Iran is under three sets of UN Security Council sanctions over its refusal to halt uranium enrichment. The country recently admitted having a second uranium enrichment site in Qom, sparking international calls for harsher sanctions.