A former United Nations chief inspector says North Korea is potentially capable of conducting a nuclear test by exploding a uranium device after using plutonium devices for previous nuclear tests.

Former IAEA Deputy Director-General Olli Heinonen said in a document he sent to Reuters that if North Korea does conduct a third nuclear test with a uranium device, it would show the world that the North has obtained enough fissile material to develop a nuclear weapon with the technology to create highly-enriched uranium.