"On January 9 and 10, 2009, Human Rights Watch researchers in Israel observed multiple air-bursts of artillery-fired white phosphorus over what appeared to be the Gaza City and Jabaliya area, HRW said.
Israel appeared to be using white phosphorus as an "obscurant" (a chemical used to hide military operations), a permissible use in principle under international humanitarian law (the laws of war).
However, white phosphorus has a significant, incidental, incendiary effect that can severely burn people and set structures, fields, and other civilian objects in the vicinity on fire. The potential for harm to civilians is magnified by Gaza's high population density, among the highest in the world, the Islamic republic news agency reported.
"White phosphorous can burn down houses and cause horrific burns when it touches the skin," said Marc Garlasco, senior military analyst at Human Rights Watch.
"Israel should not use it in Gaza's densely populated areas."
Human Rights Watch believes that the use of white phosphorus in densely populated areas of Gaza violates the requirement under international humanitarian law to take all feasible precautions to avoid civilian injury and loss of life.
This concern is amplified given the technique evidenced in media photographs of air-bursting white phosphorus projectiles. Air bursting of white phosphorus artillery spreads 116 burning wafers over an area between 125 and 250 meters in diameter, depending on the altitude of the burst, thereby exposing more civilians and civilian infrastructure to potential harm than a localized ground burst.
Since the beginning of Israel's ground offensive in Gaza on January 3, 2009, there have been numerous media reports about the possible use of white phosphorous by the Israeli military.