The South African Nuclear Energy Corporation, or NECSA, has confirmed that a kilogram (2.2 pounds) of uranium seized from two men in South Africa earlier this month was not enriched, and it probably originated from a nuclear enrichment plant outside the continent, Agence France-Presse, or AFP reported on Tuesday.

According to reports, police had arrested two Mozambican men in their early twenties for possessing uranium and 90 ecstasy tablets on Nov. 14 in the southeastern coastal city of Durban. The incident had heightened concerns about a possible illegal trade in enriched nuclear materials that could be used to make bombs.

"Yes it is uranium and the tests suggest that it must have come from a country that is dealing with some uranium enrichment at the moment, very very unlikely (in) Africa," NECSA spokesman Elliot Mulane told AFP.

Although it is not clear from where the product could have come, Mulane said that the probe will now move "across international borders."

According to test results cited by AFP, the seized material had a 0.38 percent Uranium -235 isotope content, which is the only uranium component capable of sustaining a chain reaction or nuclear fission. Mulane said the uranium content in the material was not harmful as it was not enriched and had a low U-235 content, and that it was the kind used for industrial purposes.

In natural uranium, U-235 is found in 0.7 percent levels, while for civilian use such as nuclear power reactors, the percentage of U-235 should be in the 0.8 percent to 8.0 percent range. For weapons grade uranium, U-235 content must be above 90 percent, which is achieved through the enrichment process. 

South Africa is the only country on the African continent with a nuclear power plant, but several African countries including Niger and Namibia have considerable uranium deposits and mining activities.

More than 17 countries including the U.S., China, France, Russia, North Korea and Iran are known to operate enrichment facilities, and according to a 1997 estimate from the Institute for Science and International Security, there are about 1,720 tons of highly-enriched uranium in the world.