A leak of white ?phosphorus has been detected at the Osan Air Base in South Korea. (EPA PHOTO)A leak of white ?phosphorus has been detected at the Osan Air Base in South Korea. (EPA PHOTO) Credit: AAPSouth Korean authorities have ordered civilians to relocate after a suspected white phosphorus leak at a US military base near the capital Seoul. Officials in the city of Pyeongtaek urged nearby residents to move to a safe location and avoid skin exposure after the leak at the Osan Air Base was detected about 5pm. White phosphorus is a controversial chemical substance used in incendiary munitions and smoke shells.