The volatile chairman of the militant Jewish Defense League and another of the group's top officials faced federal charges Wednesday of plotting to blow up a Los Angeles area mosque and an office of California state Rep. Darrell Issa.

Irv Rubin, 56, the group's chairman, and Earl Krugel, 59, its West Coast coordinator, were arrested late Tuesday after explosive powder was delivered to Krugel's home in Reseda, authorities said.

Other weapons and bomb-making materials were seized during a raid at Krugel's home, authorities said. Rubin, long seen as an isolated extremist by mainstream Jewish leaders, and Krugel were charged with conspiracy to destroy a building by means of an explosive, which carries a maximum five-year sentence, and possession of a destructive device related to a crime of violence, which carries a mandatory 30-year sentence.

Law enforcement authorities said the arrests followed one of the most significant investigations by the Los Angeles Joint Terrorism Task Force in its 16-year history.

"Not long after the Sept. 11 terrorist attacks, I announced my office's promise to vigorously prosecute hate crimes," John Gordon, U.S. attorney for the Central District of California, said at a news conference. "Last night's arrests confirm that we meant what we said."

The alleged plot, according to an FBI affidavit, was revealed by a JDL member who was first contacted by Rubin and Krugel in October about participating in attacks on local Arab-related institutions. In a subsequent tape-recording of a meeting at Krugel's residence, the affidavit alleges, Krugel said Arabs needed "a wake-up call" and Rubin said the JDL needed to draw more attention to itself in a "militant way."

The final plans, authorities allege, were hatched Tuesday night at an Encino delicatessen when Rubin identified Issa's office and the King Fahd Mosque in Culver City as targets and the informant unloaded five pounds of explosive powder in Krugel's garage. Minutes later, dozens of law enforcement officers arrested both men without incident -- Krugel at his home and Rubin in his car, not far from his residence in Monrovia.

At a bail hearing Wednesday afternoon, U.S. Magistrate Victor B. Kenton ordered both men held without bail pending arraignment Dec. 31. They were found to be flight risks and dangerous to the community. Outside the courtroom, relatives protested the arrests.

"My husband has been fighting terrorism all his life. This is a travesty," said Rubin's wife, Shelley. "He is a good, upstanding man who speaks his mind -- and that has gotten him in trouble in the past."

After the ruling, Krugel's lawyer, Charles L. Kreindler, said the defendants may have been entrapped.

"In the aftermath of Sept. 11, the government decided to become more proactive," Kreindler said. "In this case, they became a little too proactive. They sent in a snitch who set them up."

But Muslim and Jewish community representatives said they were shocked only at the contemptible nature of the alleged plot. "Rubin has never shied away from violent rhetoric against Arabs and Muslims," said Brian Levin, director of the Center for the Study of Hate and Extremism at Cal State San Bernardino.

David Lehrer, western regional director of the Anti-Defamation League, said Rubin was viewed with "utter contempt" in the Jewish community. "They have no constituency to speak of," he said of the JDL.

The JDL claims several thousand members nationwide but many experts on political extremism say the group is much smaller.

The alleged plot also drew strong condemnation from the purported targets, who were not notified about the threats, authorities say, because they were identified only minutes before the arrests. "As you can imagine, this is shocking news to receive," said Issa, who is of Lebanese descent. "Like most Americans, my hope is for a peaceful resolution to the Middle East conflict. Unfortunately, there are extremists on both sides who oppose a peaceful resolution, and instead choose violence."

Usman Mahda, community liaison for King Fahd Mosque, said he was shocked by the alleged plot, which comes during Ramadan, the holiest time of the year for Muslims.

"There would have been hundreds and hundreds of people [there] ... mostly American citizens," Mahda said. "It is scary. It's sad and it's disgusting. No Muslims, Jews or Christians should suffer like that."

Built in 1998, the mosque draws members from Los Angeles and Orange counties' growing Muslim community. In her affidavit, FBI Special Agent Mary P. Hogan said she was first contacted by the informant on Oct. 18 about an unsolved 1985 homicide, the bombing death of Alex Odeh, western director of the Arab-American Anti-Discrimination Committee in Santa Ana.

One year after Odeh's murder, an FBI analysis said "certain evidence" implicated former associates of Rubin's who have since emigrated to Israel. Although Rubin has always denied any involvement, he has said that Odeh "got exactly what he deserved."