Ghassan Abu Sitta, a doctor in Gaza, has said Israel is “increasingly” using phosphorous bombs in the besieged territory.

“Treated a 13 year old yesterday with distinctive phosphorus burns to both legs and thighs,” he said in a post on X.

White phosphorus is a wax-like, toxic substance that burns at more than 800 degrees Celsius (nearly 1,500 degrees Fahrenheit) — high enough to melt metal.

According to the Human Rights Watch, white phosphorous is “unlawfully indiscriminate when airburst in populated urban areas, where it can burn down houses and cause egregious harm to civilians”.