Russian authorities say they have seized radioactive material at a Moscow airport from the luggage of a passenger traveling to Iran.

The Customs Service issued a statement saying the radioactive isotope Sodium 22 was seized Friday at Moscow's Sheremetyevo International Airport.

The agency said the discovery involved 18 pieces of radioactive metal that triggered airport sensors.

Officials said the isotope can be used for medical or research purposes.

It was not immediately clear if there was any connection to Iran's controversial nuclear program, and the passenger was not detained.

Russia built Iran's first nuclear power station and has delivered nuclear fuel for the reactor.

Western nations accuse Iran of pursuing nuclear technology in order to make nuclear weapons — a charge Tehran denies.