Two barrages of mortar shells that were fired from the Gaza Strip into Israel's south on Sunday contained phosphorus, according to a letter of complaint sent by Eshkol Regional Council Chairman Haim Jelin to U.N. Secretary-General Ban Ki-moon on Tuesday.

The shells containing phosphorus, a substance that can cause severe burns upon contact with human skin, were fired Sunday morning and landed in open fields. No injuries or damage were reported.

In the letter, Jelin wrote: "[On] January 1, 2012, at 7 a.m., two salvos of mortar shells were fired from the territory of the Gaza Strip toward farmers working [in] fields in the Eshkol Regional Council. After the firing, two shells were identified on the ground and had phosphorus explosive heads. As you know, use of phosphorus as munitions directed at civilians is prohibited by the Convention on Certain Conventional Weapons."

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Decrying the ongoing rocket and mortar attacks on southern Israeli communities, Jelin firmly asked Ban to take action against Hamas.

"The Israel Defense Forces, charged with protecting the residents of the state of Israel, are criticized and judged due to their being the military of a U.N. member state. In contrast, Hamas, the 'neighborhood bully,' is not subject to international laws, and feels free to use illegal weaponry against an innocent civilian population – without being judged or criticized by any international body. I call upon you to put an end to this hypocrisy!"

Jelin added, "In the western Negev region lives an entire population that suffers the consequences of prolonged regional combat, and attention must be paid to this." He concluded that the letter was "an official complaint in the name of 13,000 residents of the Eshkol Regional Council, regarding the firing of phosphorus shells toward a civilian population."

Sunday's mortar attacks came just a few days after the IDF killed terrorist leader Muaman Abu-Daf in an air strike on the Gaza Strip. An IDF statement on Friday said Abu-Daf was a “senior operative in the Global Jihad terrorist movement” who had “orchestrated and executed numerous and varied terror attacks” against Israeli citizens and soldiers, and had been involved in preparations for an attack on the Israeli-Egypt border that was thwarted last week.

Abu-Daf headed the Army of Islam, part of a loose network of Palestinian groups that profess allegiance to al-Qaida and that have been reinforced by radical Salafi volunteers from neighboring Egypt.

The statement said the IDF targeted the terrorist squad Abu-Daf was with moments before it was preparing to fire rockets at Israel.

The latest mortar shelling raises the number of terror attacks on Israel since the Israel Security Agency (Shin Bet) released its monthly Terror and Data Trends Report, showing a surge in the number of attacks last month compared to November. Molotov cocktails and rocket fire were the predominant forms of terrorism.

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