The Israeli Ambassador to Russia admitted that Israel used white phosphorous but maintained that it was in accordance with international law.

“Phosphorous is not a prohibited component of weaponry. It was used for making smoke screens. Israel did not use white phosphorous in densely populated areas,” said Israeli Ambassador Anna Azari.

Although the use of phosphorous weapons to mask forces is permitted by international law, Amnesty International has accused Israel of committing a war crime by using it in heavily populated areas. The UN has also called for an investigation into the matter.

Israel announced on Wednesday that it is opening an investigation into whether white phosphorous was improperly used by its forces.

Meanwhile, there have been reports from all over Gaza claiming that areas were hit by phosphorous shells launched by Israel.

Palestinian doctors have reported treating dozens of victims of phosphorous attacks and Palestinian witnesses say the shells were fired at houses.

In the Palestinian city of Khoza'a, at least four people were killed as a result of phosphorous shells being fired at a large house. Citizens reported that the phosphorous burned bodies so badly that only bone was left.

The UN compound in Gaza city was hit by three shells on 15 January. Other areas claim to have been hit by up to 20 such shells.

Prominent human rights group Amnesty International, among others groups, accused Israel of a war crime and the UN said that it used the phosphorous in a way that burned civilians.

“They obviously could not have gone on denying the use of phosphorous,” Donatella Rovera, Amnesty researcher for Israel and the Occupied Territories, told the Guardian newspaper in London. "There are still phosphorus wedges burning all over Gaza including at the UN compound.

According to senior officials for Israel Defense Forces (IDF), the Army made use of two types of shells.

The first type consists of only a small amount of phosphorous and is used mainly to provide smoke screens for their forces. This use is legal according to the Geneva Convention.

The second, however, is larger and contains far more phosphorous. IDF said that 200 were used and that 180 were fired at Hamas fighters and rocket launch crews in Gaza.

Fact Box: White Phosphorous

White phosphorous is an incendiary device which produces smoke and flare. Phosphorous detonates immediately upon contact with air.

Phosphorous serves as an efficient smoke screen for masking forces, but due to it's chemical properties can cause severe injury, burns and death in humans.

White phosphorous produces a dense, hot white smoke. Upon skin contact, phosphorous can cause extensive burns. The burns carry a much larger risk of death due to the fact that the phosphorous is easily absorbed by the skin resulting in damage to the liver, heart and kidneys and in some cases, muliple organ failure.

Phosphorous is prohibited for use as a weapon by the Geneva Convention and the Convention on Certain Conventional Weapons.