JERUSALEM, May 19 (JTA) — Israel tortures 850 Palestinians per year, according to the Israeli human rights group B’Tselem. Most of the incidents, according to the group, came during interrogations of prisoners. The report was issued ahead of a High Court of Justice hearing this week on petitions to ban violent interrogations. It also came as an affidavit submitted to the court was made public in which Ami Ayalon, the head of the Shin Bet, defended the “shaking” of prisoners as an essential part of the activities of Israel’s domestic security service. “Torture of Palestinian detainees is routine and is a bureaucratic procedure,” Yuval Ginbar of B’Tselem told a news conference in Jerusalem. The group said the methods, drawn from court documents and testimony from detainees, include placing hoods and shackles on prisoners, depriving them of sleep and shaking them violently. The U.N. Committee Against Torture this week condemned Israel for the interrogation techniques, demanding that they be stopped. Moshe Fogel, the director of the Government Press Office, rejected the claim, saying Israel banned torture, and that moderate physical pressure was used only in “very special instances.” An official Israeli commission headed by a retired high court justice determined in 1987 that interrogators could use “moderate physical pressure” under specific conditions during questioning. This applied to instances termed the “ticking bomb,” in which it was believed that extracting information from a suspect could prevent a terrorist attack.