French President Nicolas Sarkozy agreed on U.S. proposal of stronger sanctions against Iran on its nuclear enrichment program, the president's office announced Monday night.

Sarkozy agreed with visiting U.S. Defense Secretary Robert Gates that "the time has come for the adoption of stronger sanctions, in the hope that dialogue could be resumed," the Elysee Palace said after the two held a near-one-hour talk.

Iran announced on Monday it has informed the International Atomic Energy Agency (IAEA) about its plan to produce 20 percent enriched uranium on Tuesday, which intensified the western countries concerns over its nuclear power and provoked fresh warning of sanctions.

Early in the day, French Defense Minister Herve Morin joined his U.S. counterpart in saying that their countries would work together for new sanctions against Iran over the nuclear issue.

French Foreign Minister Bernard Kouchner, who Gates is scheduled to meet on Tuesday, also voiced on the issue, saying "we can't apply other choice but only sanction given the negotiation is impossible."

Also on Monday, IAEA Director General Yukiya Amano expressed his concern at Iran's newly announced decision but insisted on his mediating between Iran and international communities.

The decision "may affect, in particular, ongoing international efforts to ensure the availability of nuclear fuel for the Tehran research reactor," the international nuclear watchdog said.