Israel has jailed a Jewish extremist for six months without trial as part of an ongoing crackdown against terror cells in the wake of two deadly attacks by religious fundamentalists.

Mordechai Meyer, from the West Bank settlement of Maaleh Adumim, was placed under house arrest two days prior to being given a 6-month administrative detention order on Wednesday.

Meyer is the first detainee to be jailed since Israel's Defense Minister Moshe Yaalon approved the use of administrative detention orders against Jewish extremists on Sunday. The measure, long used by Israel against alleged Palestinian terrorists, enables suspects to be jailed indefinitely without trial or knowing the evidence against them.

A statement issued by Israel's Defense Ministry said the 18-year-old radical was being held in connection to "his involvement in violent activities and recent terror attacks."

According to the country's security service, Shin Bet, Meyer was previously arrested in connection with a June arson attack on a Catholic Church in northern Israel and is also suspected of involvement in attacks on Palestinian homes.

Two other Jewish extremists have also been arrested in the last 48 hours.

Earlier on Wednesday Aviatar Slonim, a far-right activist, was detained in Beit Shemesh, a city 18 miles west of Jerusalem, on suspicion of plotting terror attacks and seeking to overthrow the Israeli government. Slonim was previously arrested in relation to an arson attack on a Palestinian home in the South Hebron Hills and has been banned from entering Jerusalem and West Bank.

On Monday evening Mier Ettinger, the grandson of the late Rabbi Meir Kahane, an extremist Israeli-American right-winger, was arrested on suspicion of leading an underground Jewish terror network. The 24 year-old's detention has now been extended until at least Sunday following a court hearing in Nazareth.

The arrests follow two lethal attacks by Jewish religious extremists in the last week. On Thursday an ultra-Orthodox extremist, Yishai Schlissel, stabbed six participants in a gay pride parade in Jerusalem killing one. Schlissel had previously been sentenced to a 12-year jail term for a knife attack at a pride event in 2005, but was released early for good behaviour. The following day a toddler was burnt to death in an arson attack on a Palestinian home in West Bank by unknown assailants who scrawled "Revenge" in Hebrew on the wall of the neighboring house.

According to officials a dozens of young Jewish extremists operating on both sides of the 1967 Green Line have been well-known to the security services for several years but politicians ignored warnings about the threat they posed.

"They read the ideology on the Internet and extremist blogs, the Shin Bet has known most of these activists by name and where they live for some time, they are familiar," Lior Akerman, a former Shin Bet head of division for internal security in the occupied territories, told VICE News. "If all these young men were sitting in administrative detention then this attack [on the Palestinian home] might not have happened... Punishments given to these Jewish fundamentalists, terrorists, are not the same as those given to Palestinian terrorists, they are not so hard. The whole legal system needs to change"

In the face of accusations of unequal treatment, Israel's Prime Minister Benjamin Netanyahu has now pledged "zero tolerance" for Jewish terrorism and authorized a series of steps, including administrative detention, to combat the trend.

The government has not yet commented on whether any of the three arrested men are suspected of direct involvement in the firebombing that killed 18-month old Ali Saad Dawabsha.

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