The IDF says it has launched an internal investigation into allegations about its use of white phosphorus weapons during Operation Cast Lead in the Gaza Strip. White phosphorus is an incendiary agent used to illuminate targets or create smoke screens. International law does not prohibit its use in battle, but it can inflict serious burn wounds. UN officials and human rights groups have alleged the army used it in the Gaza campaign. Amnesty International has branded the alleged firing of white phosphorus shells in densely populated residential areas of Gaza a war crime. Israel has not publicly acknowledged using white phosphorus. But in response to the claims, the military said in a statement Wednesday that an "investigative team has been established ... to look into this issue."