Russian Deputy Prime Minister Sergei Ivanov on Saturday urged Iran to address international concerns about its disputed nuclear program.

"No one questions Iran's right to use nuclear energy for civilian purposes, but the Islamic Republic must ease the world community's concerns about the reasons behind its nuclear research," Ivanov told reporters on the sidelines of a security conference in Munich.

Iran may face a fourth set of UN Security Council sanctions over its uranium enrichment activities, which Western powers fear are aimed at building nuclear weapons. Tehran insists its nuclear program is designed for power generation.

Ivanov said Tehran should take steps proposed by the UN nuclear agency and the Security Council. "We expect cooperation from Iran on the problem," he said.

Iran's foreign minister, Manouchehr Mottaki, said earlier on Saturday after a meeting with the head of the International Atomic Energy Agency (IAEA) that they had agreed on a plan to swap Iran's low-enriched uranium for higher-grade fuel for a research reactor in Tehran, but some issues remain to be coordinated.

IAEA Director General Yukiya Amano said he wanted dialogue with Iran to speed up, Reuters and other agencies reported.

The United States and Germany said earlier on Saturday that Tehran has so far failed to dispel their skepticism over its nuclear program. And U.S. Defense Secretary Robert Gates was reported to have said that it is time for more sanctions against the Islamic Republic.

Ivanov said any possible sanctions against Iran should be designed to stop nuclear proliferation rather than target its economy.

Russia, a veto-wielding Security Council member, has been involved in the long-running nuclear dispute with Iran, along with the other five mediators, Britain, China, Germany, France and the United States. China has been reluctant to back tougher sanctions.