Israeli police said they detained on Monday an Arab Israeli suspected of supporting the Islamic State group, in one of the Jewish state's first arrests related to the jihadist organisation.
The 24-year-old from the village of Kafr Kara, in northern Israel, was picked up near Tel Aviv, police spokeswoman Luba Samri told AFP, without naming him.
Israeli public radio said that he was a teacher of Islamic studies at a Kafr Kara high school.
Police said that a search of his home turned up an IS flag and jihadist literature.
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Haaretz newspaper reported last week that another Arab Israeli, Ahmad Shurbaj, was charged in May for fighting for the group in Syria.
Israel borders Syria where IS controls a swathe of territory in the east including most of the war-ravaged country's main oil fields.
Israel this month added IS to its list of outlawed organisations, including its members, financial backers and sympathisers.
Samri said that although the teacher arrested Monday was the first person taken into police custody for alleged IS links, the Shin Bet domestic security service is investigating others.
The 24-year-old man charged in May is believed to have travelled to Syria by way of Turkey in January and was arrested at Israel's Ben Gurion airport on his return on April 20, Haaretz wrote.