Terrorists from the Islamic State (ISIS) jihadist group have advanced plans to murder Jewish children in Turkey, targeting kindergartens and schools and youth centers, Britain’s Sky News revealed on Monday. According to the network, information on what intelligence officials are describing as "an imminent" attack against Jewish targets in Turkey was obtained from six ISIS operatives who were arrested in the southern city of Gaziantep over the last week. The most likely target of an attack is Istanbul's synagogue in Beyoglu, which also has a community center and a school attached to it. "In light of these circumstances, extraordinary security measures are being taken above and beyond the high alert level already in place by the Turkish police, as well as vigilance within the Jewish community," an intelligence source told Sky News . "Undercover and other covert counter-terror measures are being implemented around the clock,” the source added. "This is a more than credible threat. This is an active plot.” The report comes days after the Turkish police issued a warning on Saturday night, according to which ISIS was planning to attack synagogues and churches during the Christian holiday of Easter. In that warning, police said Jews and Christians are likely to be targets of attacks. That warning came just one week after an ISIS suicide bomber tracked Israeli tourists in Istanbul and detonated an explosive among them, murdering three Israelis as well as an Iranian, and wounding 39 others including 11 Israelis. The three murdered Israelis were Simcha Damari, Yonatan Suher and Avraham Goldman. An intelligence report seen Monday by Sky News said, "The so-called Islamic State is believed to be behind both sets of attacks and the organization continues in determined efforts to perpetrate further attacks in Turkey and elsewhere." The threat against Jewish targets, intelligence sources said, was the best information gathered on an imminent attack. "We don't know when it's scheduled for. It could be in the next 24 hours or next few days," the source said. Monday’s report also came hours after Israel increased its security warning for citizens traveling to Turkey. The warning was at level 3 (basic concrete threat) and will now be set at level 2 (high concrete threat). In practical terms, this means that the Counterterrorism Office advises the Israeli public to avoid visiting the country and suggests that citizens currently in Turkey leave as soon as possible.