Special report: Palestine-Israel Conflicts 

    TEHRAN, Jan. 18 (Xinhua) -- Iran is seeking for United Nations' serious action over Israel's use of chemical weapons in Gaza, the semi-official Fars news agency reported.

    Foreign Minister Manouchehr Mottaki made the accusation against Israel in a letter to UN Chief Ban Ki-moon, urging for a "serious and effective action" over Israel's use of chemical weapons in Gaza, according to the report.

    "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 was quoted as saying in the letter.

    He also called the use of the chemical weapons as the "examples of war crimes."

    Earlier on Tuesday, Iran's Ministry of Defense and Armed Forces Logistics also issued a statement to denounce the Israeli use of chemical weapons in Gaza, saying that "the Zionist regime" had fired "white phosphorus into Gaza."

    "According to the Geneva Protocol 1925, using the poisonous gases is forbidden," the statement said.

    Geneva Protocol 1925 prohibits the use of asphyxiating, poisonous or other gases, and of bacteriological methods of warfare declared in Geneva on June 17, 1925.

    After about three weeks of an unprecedented military air and ground offensive of Israel on Gaza since Dec. 27, where around 1,240 Palestinians killed and more than 5,200 others wounded, Israeli Prime Minister Ehud Olmert declared a unilateral ceasefire in the Hamas-ruled Gaza Strip, beginning from 2 a.m. (0000 GMT) Sunday.

    "We have reached all of our objectives in Gaza," Olmert told a press conference in Tel Aviv, adding that Hamas has been dealt a heavy blow and its leaders are now in hiding.

    However, on Sunday morning, hours after the unilateral ceasefire went into effect, southern Israel was pounded by a number of rockets fired from Gaza and the Israeli army confirmed that it opened fire after Gazan militants attacked Israeli troops in the Palestinian enclave.

    At least one Palestinian was reportedly killed by the exchange of fire on Sunday morning.