Israel has jailed a Jewish extremist for six months without charges or trial, expanding a crackdown against militant Jews and deploying a contentious measure typically used for Palestinians suspected of staging attacks.

This was the first time the measure, known as administrative detention, was applied against an Israeli since the crackdown began following a pair of deadly attacks last week.

Defense Minister Moshe Yaalon signed an order late Tuesday that jails extremist Mordechai Meyer, from the West Bank settlement of Maaleh Adumim, for six months.

A statement from Yaalon's office said Meyer, who Israeli media reported to be 18 years old, was being held in connection to "his involvement in violent activities and recent terror attacks."

The ministry would not elaborate on the suspicions against him, but Israel's internal security agency Shin Bet said Meyer was among five people arrested in connection with the arson attack against an important church in northern Israel in June, although he was not indicted.

Meyer was also suspected of links to attacks against another church in Jerusalem, as well as attacks on Palestinian property, the agency said, adding that he had previously been banned from the West Bank and Jerusalem. The Shin Bet declined to comment on whether Meyer was connected to last week's attack on a Palestinian home.

2 deadly attacks last week

The detention intensifies a crackdown on Jewish militancy that came after two deadly attacks last week.

On Friday, suspected Jewish extremists torched a West Bank home, an arson attack in which a Palestinian toddler was burned to death and his parents and 4-year-old brother were seriously wounded. A day earlier, an anti-gay ultra-Orthodox man stabbed six people at Jerusalem's Gay Pride parade, and one of them — a 16-year-old girl — later died of her wounds.

Prime Minister Benjamin Netanyahu has pledged "zero tolerance" for Jewish terrorism and Israel authorized a series of steps, including administrative detention, to help stamp out the trend.

On Tuesday, authorities also arrested Meir Ettinger, a high-profile activist accused of leading a new movement of defiant settler youths who embrace violence and reject the rule of law in the name of the purity of the Holy Land.

Ettinger, 23, was not being held under administrative detention but was arrested for "involvement in an extremist Jewish organization." The Shin Bet security agency would not say if Ettinger is also suspected in the West Bank arson attack.

Administrative detention is typically used against Palestinians who can be held for months or even years without trial or charge. The measure is rarely applied against Israelis. Israel has defended the administrative detention of Palestinians as a necessary tool for preventing militant attacks.

Meyer's lawyer, Adi Keidar, told Israeli Army Radio that there were "less drastic steps" Israel could use to pursue an investigation against his client. He said he opposed the measure, both for Israelis and Palestinians.

"Legally speaking, you can't take a person and put him in jail, without having evidence against him," Keidar said.