Special report: Palestine-Israel Conflicts

    JERUSALEM, Jan. 6 (Xinhua) -- An Israel Defense Forces (IDF) officer was killed overnight possibly by friendly fire in the Hamas-ruled Gaza Strip, adding to another three deaths in a similar incident, said the IDF on Tuesday.

    "Details of the event are still being investigated. However, it is suspected that a tank shell was mistakenly fired at the force," said the IDF on the incident in northern Gaza, where Israeli troops are engaged in fierce fighting with Gazan militants.

    Another three soldiers from Israel's elite Golani Brigade were killed on Monday in a similar friendly fire incident, which also saw 24 others injured, with one of them in critical conditions, marking the army's biggest single death toll since the IDF launched the ground incursion on Saturday night.

    The two incidents increased the overall death toll on the Israeli side to nine. Four of them died in rocket attacks by Gazan militants before the ground offensive, and the other five were killed in the ground battle.

    More casualties are likely as Israeli troops move into densely populated urban areas in the coastal Palestinian enclave, where over 540 have been killed and some 2,500 others injured since Israel's Operation Cast Lead kicked off on Dec. 27.

    Israeli Defense Minister Ehud Barak said Monday that the assault will continue until the goal of restoring security to southern Israel is realized. He earlier told the Israeli public that such efforts might mean Israel would have to pay a heavy cost.