The IDF rejected accusations on Sunday that it was using illegal weaponry in its war against Hamas in the Gaza Strip. The Human Rights Watch said Sunday that the IDF had fired artillery shells packed with the incendiary agent white phosphorus over populated areas of Gaza, including a crowded refugee camp, putting civilians at risk. Researchers from the rights group said they witnessed hours of artillery bombardments on Friday and Saturday afternoon from Israel's border in which shells burst over the Jabalya refugee camp in northern Gaza, sending out trails of burning smoke that indicates the shells contained white phosphorus. The substance can cause serious burns if it touches the skin and can spark fires on the ground, the rights group said in a written announcement calling on Israel not to use it in crowded areas of Gaza. In response to the accusations, the IDF released a statement saying that it only used "munitions in accordance with international law."