Russia says again it will not agree to sanctions against Iran until Moscow sees hard evidence that Tehran's nuclear program is not for peaceful purposes.

Itar-Tass news agency quotes a Russian Foreign Ministry spokesman Mikhail Kamynin as saying Russia will be able to talk about sanctions after seeing "concrete facts" about Iran's nuclear activities.

Russia has said the International Atomic Energy Agency should be allowed to handle the Iranian dispute. However, the United States said Thursday that momentum is shifting toward the imposition of U.N. sanctions against Iran.

A U.S. State Department spokesman, Sean McCormack, said without a major change in Iran's attitude, Washington will seek a U.N. resolution to require Tehran to suspend its uranium enrichment program.

This week, the five permanent U.N. Security Council members and countries from the Group of Seven major industrial powers plus Russia met in Moscow to discuss the dispute. The meeting was widely reported to have ended inconclusively.

Late last month, the Security Council ordered Iran to stop enriching uranium. The I.A.E.A. is due to present a report on Tehran's compliance to the Council April 28.

In other news, Russia rejected a call by the United States to halt construction of a nuclear power plant in Iran.

Reactor building of Iran's Bushehr nuclear power plant (file photo)

Russian atomic energy chief Sergei Kiriyenko defended the Bushehr project, saying work on the 800 million-dollar plant is in full compliance with the Nuclear Non-Proliferation Treaty.

The United States alleges Iran is seeking to build an atomic bomb - a charge Tehran denies.