By Barak Ravid and Yuval Azoulay,
Israel's Counter-Terrorism Bureau on Thursday issued an advisory warning Israelis abroad to be vigilant in the face of likely abduction attempts, as Lebanese guerrillas threatened to avenge Tuesday's assassination of a Hezbollah commander tied to a string of terror attacks against Israeli, American and Jewish targets.
Israel also ordered its military and embassies to go on alert Thursday, and advised Jewish institutions worldwide to follow suit, as Hezbollah leader Hassan Nasrallah vowed to retaliate against Israeli targets.  
Israel on Wednesday denied involvement in the death of Imad Mughniyah, who was killed in a car bombing Tuesday in the Syrian capital of Damascus.
The slain Hezbollah deputy secretary general was on Israel's and the U.S.'s wanted terrorist lists, and Hezbollah, its Iranian backers and others pointed accusatory fingers at Israel following the assassination.
Israel Defense Forces Chief of Staff Gabi Ashkenazi put forces on heightened alert, instructing them to take the necessary precautions by air, land and sea in order to protect the northern border and other Israeli interests, the army said Thursday.
The military sent more troops to the already heavily patrolled northern border with Lebanon, defense officials said, without elaborating. Soldiers were ordered to be on guard for attacks on both the border with Lebanon and in the Palestinian territories.
The Prime Minister's Office issued a statement saying that "Hezbollah is accusing Israel again and again in the death of Mughniyah. Therefore, the danger of Hezbollah carrying out terror attacks against Israeli targets abroad is escalating."
The Counter-Terrorism Bureau also issued travel warnings against traveling in places abroad where there are high concentrations of Israelis, especially tourist attractions.
The bureau advised Israelis traveling abroad to be especially alert and pay attention to any abnormal occurrences. It also advised Israelis to avoid traveling to any Arab or Muslim nation that a travel advisory has already been issued for. Finally, the bureau stressed that Israelis should resist any seemingly tempting opportunity originating from an unknown source abroad, and refuse any unexpected gifts.  
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