The Pentagon's confirmation that it used white phosphorus as a weapon during last year's offensive in the Iraqi city of Falluja has sparked criticism.

White phosphorus: What are its effects?

If particles of ignited white phosphorus land on a person's skin, they can continue to burn right through flesh to the bone. Toxic phosphoric acid can also be released into wounds, risking phosphorus poisoning.

Skin burns must be immersed in water or covered with wet cloths to prevent re-combustion until the particles can be removed.

Exposure to white phosphorus smoke in the air can also cause liver, kidney, heart, lung or bone damage and even death.

A former US soldier who served in Iraq says breathing in smoke close to a shell caused the throat and lungs to blister until the victim suffocated, with the phosphorus continuing to burn them from the inside.

Long-term exposure to lesser concentrations over several months or years may lead to a condition called "phossy jaw", where mouth wounds are caused that fail to heal and the jawbone eventually breaks down.


What are the international conventions?

Washington is not a signatory to any treaty restricting the use of white phosphorus against civilians.

White phosphorus is covered by Protocol III of the 1980 Convention on Conventional Weapons, which prohibits its use as an incendiary weapon against civilian populations or in air attacks against enemy forces in civilian areas.

The US - unlike 80 other countries including the UK - is not a signatory to Protocol III.