Challenges to Israel's justice system by a small group of ultra-nationalist rabbis have raised the specter of theocracy in Israel, where religion is deeply intertwined with affairs of state.

Over the past week, police have detained, questioned and released two very influential rabbis as part of an ongoing investigation into a banned book called "The King's Torah," which justifies killing non-Jews under certain circumstances.

The arrests have sparked violent protests and a raging debate about whether rabbis are above the law, and about the limits of religious freedom of expression.

Both rabbis, Dov Lior and Yaakov Yosef, say they are victims of the lay justice system, which seeks to limit their authority by refusing to accept opinions based on scripture and rabbinic tradition.

Their supporters argue that the arrests could set a dangerous precedent that would clamp down on rabbinical opinion in the name of the fight against racism.

Following Yosef's arrest on Sunday, around 1,000 of his supporters took to the streets of Jerusalem, burning bins and blocking roads before being dispersed by mounted police.

And on Monday, around 2,000 people massed outside the Supreme Court -- the symbol of secular law -- to protest the arrests.

"I have come here to bring the message that the laws of the Torah are above the laws" of the state, said Shmuel Eliyahu, a rabbi from the hilltop town of Safed in Galilee, which is an important center of Jewish mysticism.

Last year, Eliyahu issued a religious ruling calling on Jews not to rent or sell property to Palestinian citizens in a move that sparked outrage and deep concern in Israel.

Following Sunday's protests, the Maariv newspaper warned of the rise of "a new current in Judaism which seeks the death of the rule of law."

Israel, it said, had turned into "the only country in the world where religious figures are above the law and where the police have no right to question them."

Israel's political leaders were also quick to condemn the attitude of the rabbis and their followers. Opposition chief Tzipi Livni told army radio that they were acting as a group which "refuses to recognize the authority of judges and wants to replace them with rabbis."

Their actions, she argued, hit "at the roots of the State of Israel" -- which defines itself by law as Jewish and democratic.

"Israel is country of law and order," Prime Minister Benjamin Netanyahu insisted Sunday, implicitly criticizing the attitude of the two rabbis, who were detained after repeatedly ignoring police summonses to come for questioning.

"Nobody in Israel is above the law, and I demand that each and every citizen respect the law," he told cabinet ministers.

Even Ovadia Yosef, spiritual leader of the ultra-Orthodox Sephardic party Shas and father of Yaakov Yosef, was critical of his son's attitude to the police.

"Why does this idiot not respond to a police summons," he was quoted as saying by all the main Israeli newspapers and websites.

Both Yosef and Lior were detained in connection with their endorsement of a controversial theological treatise called "The King's Torah."

The book reportedly says babies and children of Israel's enemies may be killed in certain circumstances since "it is clear that they will grow to harm us."

It also says non-Jews are "uncompassionate by nature" and that attacks on them "curb their evil inclination."

"Anywhere where the influence of gentiles constitutes a threat to the life of Israel, it is permissible to kill them," the rabbis wrote.

The book, published earlier this year, has drawn sharp criticism from many rabbis who say it contradicts the teachings of Judaism.

Lior, who was briefly detained last week in a move which also sparked mass protests, is the spiritual leader of Kiryat Arba settlement as well as of the Jewish settlements located in the heart of the West Bank city of Hebron.

In 1995, he cursed then-prime minister Yitzhak Rabin for his willingness to make concessions to the Palestinians, and his teachings are thought to have influenced Yigal Amir, the Jewish student who went on to assassinate the premier in November of that year.