Extreme right-wing activist Meir Ettinger, held in administrative detention by Israel over alleged connections to violent attacks, on Thursday started a hunger strike in protest of his detention in solitary confinement.

Ettinger, the 23-year-old grandson of assassinated far-right rabbi Meir Kahane and the alleged leader of extremist settlers, was jailed without trial in August during a crackdown after the home of a Palestinian family was firebombed in the West Bank village of Duma. Three members of the family — mother, father and 18-month-old baby — were killed. Only four-year-old Ahmad survived, and is currently being treated in Israel for massive burns.

Two other Jewish far-right activists, Eviatar Slonim and Mordechai Mayer, were also detained and placed under administrative detention, in line with the Defense Ministry’s orders.

Slonim was also placed in solitary confinement, but Mayer’s detention in solitary was delayed because of a last-minute appeal by his lawyer.

The Israel Prison Service refused to elaborate why Ettinger had been placed in solitary confinement and denied access to a telephone, saying it was due to considerations of the agency’s intelligence unit, Ettinger’s lawyer told Channel 2.

Ettinger said he would continue his hunger strike until he is given permission to call his wife.

“We are dismayed to see worsening conditions for Jewish administrative detainees,” his lawyer Sima Kochav said, “especially when it takes place without motive or reason. The measure is unlikely, disproportionate and illegal.”

Ettinger stands suspected of incitement, conspiracy, being behind the arson of the Church of the Multiplication of the Loaves and Fishes, and the firebombing of the Dawabsha home at the end of July, his lawyer said after his arrest in August.

The far-right activist has had previous run-ins with the authorities. He was imprisoned for six months in the “spy affair” of 2012, for collecting intelligence about the plans of the Israel Defense Forces to evacuate settlements. In January 2014, he was held captive by Palestinian villagers for more than two hours, along with several other settlers who had been with him at the time of an alleged attempted “price tag” hate-crime attack. He had been living in Safed in the months before his detention after authorities ordered him to stay away from the West Bank and Jerusalem.

Simona Weinglass contributed to this report.