Likud MK Miki Zohar was questioned under caution on Thursday for four hours on suspicion of extorting Attorney General Avichai Mandelblit.
The Israel Police said that, "the investigation is being conducted with the approval and cooperation of the State Prosecutor's Office" and that they "would not be able to provide further details."
Zohar on Thursday posted on Facebook: “A sad day for our democracy. I was called in for questioning by the police in the Mandelblit case. I will not hide the fact that I was surprised, probably in light of the fact that this is an investigation to silence me based on my expressing a position in a radio interview. In my humble opinion, this is a delusional investigation against an elected official in general and an elected official from the right in particular."
The coalition chairman added: "In recent years, I have led an uncompromising dialogue regarding the conduct of the State Prosecutor's Office and the police. I did so without fear - despite all the warnings I received. 'Be careful, they'll try to stitch you up,' I was warned. And I replied: 'I will always go with my truth, and whatever the price may be'.
"I knew that as a right-winger who fought for the truth for us all that I might pay the price, but it seems that I had no idea how far they would go in trying to threaten me.
"I have never committed a criminal offense, I have never been investigated by the police and I have never been suspected of anything and if this is my first investigation, I'll take it.
"I believe that the decision of the prosecution and the police to open an investigation against me in order to prevent me from criticizing Mandelblit's conduct will be detrimental to the judicial system and may even lead to a complete loss of public trust which is already at an all-time low."
Last month, Zohar criticized Mandelblit in an interview on 103FM Radio, saying that "there would be an earthquake" if he did not resign and cancel the indictment against the prime minister.
He was referring to a recording revealed a day earlier of a 2016 conversation between Mandelblit and the disgraced former head of the Israel Bar Association Efi Nave, who is currently facing his own criminal charges. In the conversation, the attorney general is heard slamming then-state prosecutor Shai Nitzan.
If you don’t quit, Zohar said to the attorney general on the radio, if you don’t drop the criminal charges against Netanyahu, more recordings will be revealed.
Netanyahu immediately distanced himself from Zohar's comments and shortly afterwards the coalition chair himself retracted his threat.
Public Security Minister Amir Ohana, also of Likud, expressed support for Zohar on Twitter, writing: "I agree with you Miki, my dear friend. Regarding investigations into public figures, I can probably not instruct the police who to investigate, but this is a badge of shame for the police, the Attorney General and the State Attorney's Office that an investigation was conducted into an unsuccessful statement in a radio interview that was clarified afterwards. pure shame."
Likud's Transport Minister Miri Regev also slammed Zohar's interrogation.
"When will someone from the State Prosecutor's Office be questioned about things they wrote and did?" she said. "Rest assured, it will never happen because there is no one to investigate or criticize the prosecution. They are above the law."