Israeli defence officials have warned that Iranian agents may carry out terror attacks against Israeli citizens in Istanbul this weekend.
High-ranking officials claim to have concrete indication such attacks are planned, according Israeli media reports.
Israeli tourists were advised to leave Istanbul as soon as possible, or to stay in their hotel rooms, lock the doors and not open them to strangers.
There are reportedly some 2,000 Israelis in Turkey.
Israel issued a travel warning for Turkey at the end of May due to the threat of attacks, after Iranian President Ebrahim Raisi vowed retaliation for the assassination of a senior officer in Iran's Revolutionary Guards (IRGC) in Tehran.
Searches for assailants
Israeli and Turkish security forces carried out searches for potential assailants in Istanbul on Friday, according to the reports.
Israeli newspaper Haaretz reported that there were several terror cells believed to be involved in planning the attacks, making it harder for security forces to prevent them.
Recently, Israeli intelligence agencies claim to have prevented several attacks planned by Iran, including one to assassinate a US general in Germany.