"In recent attacks by the Zionist regime's troops on Gaza, the regime's army has several times used banned weapons, including dangerous, toxic materials causing painful deaths, incapacitation or physical inabilities," Mottaki said in his letter.
"According to witnesses and media reports, the lethal weapons employed in Gaza contained poisonous chemicals and other banned materials," the letter said, adding, "and medical examinations conducted on some of the victims of this kind of weapons disclosed that the type of weapons used (in the war on Gaza) contained very dangerous chemical agents causing severe cramps and convulsion, muscle spasm, vomiting, amnesia or partial loss of memory and mental disorders in addition to severe burns and injuries on the victims' eyes and respiratory organs."
"These crimes are examples of war crimes", Mottaki said.
These actions along with other examples of the violation of international laws indicate the Zionist regime's continued ignorance of international rules and principles, Mottaki wrote in his letter.
Stressing that the international law has banned use of such dangerous chemical elements and toxic materials, he added that use of asphyxiating gases, toxic gases and biological weapons have been banned by the 1925 Geneva convention and that using this kind of weapons is a flagrant violation of the 1949 Geneva Conventions on human rights.
Also in his letter, the Iranian foreign minister reminded that the Zionist regime as a signatory to the Chemical Weapons Convention should not act contrary to the object and purpose of that Convention.
The use of those agents and materials against the defenseless people in Gaza indicates the regime's intentional gross negligence of such clear obligations, Mottaki said.
He added that Iran expects the competent international organizations such as the Untied Nations to adopt the required measures and fulfill their legal responsibilities for initiating an investigation into the evidence of the tragedy and urgently dispatching assistance to the victims of the attacks.