(Adds Israeli comment, background)
JERUSALEM, Jan 10 (Reuters) - A leading human rights group on Saturday accused Israel of using white-phosphorus munitions during its offensive in the Gaza Strip and warned of the risk to Palestinian civilians who live near the fighting.
Human Rights Watch said in a statement that its researchers in Israel observed multiple air-bursts on Jan. 9 and Jan. 10 of artillery-fired white phosphorus near the city of Gaza and the Jabalya refugee camp.
The group said Israel appeared to be using the munitions to make smoke screens to hide military operations — "a permissible use in principle under international humanitarian law".
But Human Rights Watch said the practice should be stopped in Gaza’s densely populated areas.
"White phosphorus can burn down houses and cause horrific burns when it touches the skin," said Marc Garlasco, senior military analyst at Human Rights Watch.
The Israeli army said it would not provide details about the munitions it was using in the Gaza Strip, but it added: "We emphasise that the IDF (Israeli army) only employs weapons permitted by international law".
Israel confirmed in 2006 that it had used phosporus shells during its war against Hezbollah guerillas in Lebanon.
White phosphorus munitions are not considered chemical weapons. The substance ignites easily in air at temperatures of about 30 Celsius (86 Fahrenheit) and its fire can be difficult to extinguish.
Human rights organisations have long urged a world ban on the munitions, saying they cause undue suffering through severe burns.
The U.S. military acknowledged using white phosphorus munitions during a 2004 counterinsurgency offensive in the Iraqi city of Falluja. It likewise defended their use as legal.
A protocol to the 1980 Convention on Conventional Weapons forbids using incendiary weapons against civilians or against military targets amid concentrations of civilians. (Reporting by Adam Entous and Ari Rabinovitch; Editing by Mark Trevelyan)