Russia on Friday seized a consignment of the radioactive isotope Sodium-22 used for medical and research purposes at a Moscow airport from a Tehran-bound passenger, the customs service said.

"Tests showed that the Sodium-22 could only have been obtained as the result of the work of a nuclear reactor," it said in a statement. "A criminal enquiry has been opened and the materials transferred to prosecutors."

Customs had been alerted by a warning system at Sheremetyevo airport ahead of the Moscow to Tehran flight that background radiation in the departures hall was 20 times the norm. A passenger's bag was then searched.

"Eighteen metallic objects of industrial origin were found, packed into individual steel boxes," it said.

"Tests then found that the objects were in fact the radioactive isotope Sodium-22 that had been machine-produced."

No further details were immediately available on the consignment or the identity of the passenger who was carrying the materials.

Spokesman for Russian state nuclear agency Rosatom Sergei Novikov said Sodium-22 was used for medical and research purposes and produced in so-called cyclotrons, a type of particle accelerator, and not in nuclear reactors.

"There are a lot of cyclotrons in Russia," he told AFP, adding that they were used in medical and educational establishments where security levels were not as tight as those at nuclear reactors.

Rosatom only supplies Iran with medical isotopes, molybdenum-99 and iodine-131, Novikov added, without providing further details.

Russia has relatively close ties with Iran and has built its first nuclear power station in the southern city of Bushehr. Moscow has also delivered the nuclear fuel for the reactor.

Moscow has echoed Western concerns about the nature of the Iranian nuclear programme but has stopped short of publicly accusing Tehran of seeking atomic weapons and always said that the standoff should be solved by diplomacy.

Experts have long called for tight controls against nuclear smuggling so Iran cannot get hold of materials it is barred from obtaining under UN Security Council sanctions.

South Korea announces new sanctions on Iran
Seoul (AFP) Dec 16, 2011 - South Korea Friday joined a fresh multinational effort to press Iran to scrap its suspected nuclear weapons programme, adding more than 100 names to a financial blacklist of Iranian firms and individuals.

The measures announced by the finance ministry did not include a ban on imports of petrochemicals or crude oil, in what one analyst saw as an attempt to protect its economic ties with the Middle Eastern nation.

The ministry said it has added 99 Iranian firms and six individuals to 24 individuals and 102 Iranian entities blacklisted by Seoul in September last year.

Those on the blacklist will require approval from South Korea's central bank before conducting any foreign currency transactions.

The ministry said it would alert domestic companies importing petrochemicals of the risks they face because of US sanctions.

Britain, Canada and the United States slapped sanctions last month on Iran's financial, petrochemical and energy sectors following a UN nuclear agency report that strongly suggested Tehran is researching atomic weapons.

Robert Einhorn, the US State Department's special adviser for non-proliferation, visited Seoul last week and said US allies should ban petrochemical imports from Iran.

But he ruled out a need for Seoul to halt imports of Iranian crude, which make up 8.3 percent of its total needs.

The US is South Korea's key ally and stations 28,500 troops in the country to protect it from North Korea. But Iran is one of the South's top trade partners in the Middle East.

Any reduction or halt in Iranian crude imports would likely disrupt the Korean economy and complicate its efforts to hold down inflation.

Samsung Economic Research Institute analyst Bahng Tae-Seop said South Korea apparently took milder steps than anticipated due to its trade with Iran.

"Compared to the sanctions imposed last year, today's additional measures are not seen as strong pressure on Iran," he told AFP.

"South Korea is not taking the lead in imposing sanctions due to its economic ties with Iran," Bahng said, adding it would watch the international trend and try to protect its interests through diplomacy.

In addition to the initial blacklist, South Korea last year strengthened inspection of cargoes related to Iran, restricted new investment in its oil and gas industry and reduced export guarantees for shipments there.

In October 2010 it suspended the operations of Iran's Bank Mellat for two months for violating laws on foreign exchange transactions.