JERUSALEM, Nov. 17 (Xinhua) -- Israeli Prime Minister Benjamin Netanyahu said Iran poses a "grave threat" for Israel, when he visited a navy base near the north port city of Haifa on Tuesday.

    "The threat that Iran poses is very grave for the state of Israel, for peace in the Middle East and the whole world. Without any doubt, we are the first target, but not the last," Netanyahu told reporters when aboard INS Eilat, a Sa'ar-5 class vessel.

    He urged the world "to act with determination" on the Iran issue.

    Israel regards Iran as one of its main security threats, and has so far refused to rule out the option of taking military action against Iran's nuclear sites.

    The Jewish state, along with the United States and some other countries, has been accusing Iran of secretly developing nuclear weapons under the guise of civilian programs. While Iran insists that its nuclear plan is only for peaceful purposes.

    Iran also has suggested in the past that the Middle East should be free from all nuclear weapons, referring to Israel which is widely suspected to possess nuclear weapons.

    During Tuesday's visit, Netanyahu toured an Israeli navy's dolphin submarine and the battleship Eilat. As an awkward moment for the prime minister, he slipped and narrowly fell into the sea when boarding an inflatable boat.