Investigators from the Moriah Station of Israeli Police arrested a man, 25, on suspicion of threatening to cause bodily harm to MK Eli Yishai.
The man was one of dozens of hareidi Shas supporters who stormed Yishai's press conference Monday night at the Ramada Hotel in Jerusalem, where he announced the establishment of his new party Yachad.
The Shas supporters expressed their anger over Yishai's so-called defection by screaming, engaging in physical fights and threatening Yishai.
One Shas supporter took the stage just before Yishai was about to speak, grabbing the framed photograph of Rabbi Ovadiah Yosef tz"l, and screaming, "Maran [Yosef] is with us, with Shas!" to loud cheering from fellow Shas supporters.
"We have blood in our eyes," the supporters shouted. "There is no separation between the goal and the means. Yishai is a zero. We will hurt him!"
Security at the press conference were forced to take Yishai away as the men were ousted from the hall. However, clashes broke out soon afterwards, and several scuffles were reported between Yachad and Shas supporters. Polic were called to the scene.
The young man, who was arrested Monday, was brought to Jerusalem Magistrate's Court Thursday at 12:00 p.m. where police are requesting extend his detention.
Following the incident, on Tuesday, Knesset Police Commander Yossi Griff assigned Yishai an extra security detail.