Tel Aviv, June 14 : Israel's National Security Council raised its travel warning for Istanbul, Turkey's largest city, to the highest level, citing possible attacks by Iran. The warning comes amid the latest surge in tensions between Iran and Israel, reports Xinhua news agency. "Given the continuing nature of the threat and in light of the increased Iranian intentions to attack Israelis in Turkey, especially Istanbul, the National Security Council has raised the travel warning for Istanbul to the highest level, Level 4," the Council said in a statement late Monday. It called on Israelis currently in Istanbul to leave the city and Israelis planning to travel to Turkey to avoid doing so until further notice. The statement noted that other areas in Turkey are under a Level-3, or intermediate travel warning, advising Israelis to avoid "non-essential travel" to the areas. Hours before the statement was issued, Foreign Minister Yair Lapid called on Israelis in Turkey to leave the country as soon as possible and others to cancel planned visits. He added the warning followed "a situation assessment" that had found out attempts by "Iranian forces" to kidnap or kill Israeli nationals in Turkey. Israeli officials on Sunday said Turkish authorities had thwarted an "Iranian plot" to attack Israelis in Turkey last month. Iran did not immediately comment on the allegations. Iran has accused Israel of killing on May 22 Hassan Sayyad Khodaei, an Islamic Revolution Guards Corps colonel shot and killed by two motorcyclists in the east of Tehran, and has vowed to avenge his death. /IANS