Radical cleric Sheikh Raed Salah, who heads the outlawed northern branch of the Islamic Movement, was questioned by police on Wednesday on suspicion of incitement to violence and terrorism, as well as over support for or activity in an unlawful association.
Saleh is currently serving a nine-month jail sentence after being convicted of encouraging violent attacks and inciting racism in a 2007 sermon. He is to be released from prison next month.
The radical cleric has in the past labeled Israeli leaders “terrorists” and “enemies of Allah” in a speech to Muslims in Be’er Sheva, and was also jailed for five months in 2010 for spitting at an Israeli police officer.
Salah has continued his rhetoric even after he was convicted of incitement. Last February he accused Israel of being "racist" and claimed it had adopted racist policies against Israeli Arabs.
In November, Saleh announced that he was starting a hunger strike to protest his being held in isolation.
Hunger strikes are a tactic often used by terrorist prisoners in an attempt to pressure Israel to free them. Israel has several times in the past caved to the pressure and released some hunger strikers.