The two mortar shells that Gaza terrorists fired at the western Negev Sunday morning contained phosphorus – a substance that causes burns upon contact with human skin. Police sappers discovered the substance upon analyzing the exploded shells.

The Gaza Arabs have fired phosphorus shells in the past. The last time this occurred was in August, when a mortar shell containing the substance was fired at Kerem Shalom.

In March as well, a barrage of shells from Gaza included shells that held phosphorus.

International law forbids the use of phosphorus against anything but a military target that is isolated from civilian population.

Israel was accused of using phosphorus shells at one point in Gaza during its Cast Lead counter-terror operation in late 2008 and early 2009.

Israel explained that the shells were used in an emergency situation, in which Givati Brigade soldiers were trapped in a dangerous situation and had to be extricated.