The University of California went to court Thursday to try to keep animal rights activists away from UCLA employees who say they have been threatened because of their research.

Three times since June 2006, Molotov cocktail-type devices have been left near the homes of faculty members who oversee or participate in research that involves animals, according to a statement from the University of California, Los Angeles.

Researchers' homes have also been vandalized and they have received threatening phone calls and e-mails, according to the university. On at least one occasion a faculty member received a package rigged with razor blades, the statement said.

"Enough is enough," UCLA Chancellor Gene Block said. "We're not willing to wait until somebody is injured before taking legal action to protect our faculty and administrators from terrorist tactics, violence and harassment."

The University of California's Board of Regents filed suit in Superior Court in Santa Monica on Thursday, seeking a temporary restraining order and permanent injunctions keeping activists away from the researchers, university spokesman Phil Hampton said. The board oversees the state's 10 University of California campuses.

Hampton said the suit specifically requests restraining orders and injunctions against the Animal Liberation Front, the Animal Liberation Brigade, the UCLA Primate Freedom Project and five protesters believed to be affiliated with those groups.

The suit alleges that the defendants invaded researchers' privacy, interfered with business practices and intentionally caused emotional distress. It also asks the court to prohibit the defendants from vandalizing their property, violating local noise ordinances or disseminating personal information about university personnel over the Internet.

Jerry Vlasak, a spokesman for the Animal Liberation Press Office, said any pickets named in the suit have a constitutional right to protest. As for the underground protesters, he said they would not be intimidated by the lawsuit.

"Here they are risking 30-year sentences for arson and they're going to be threatened by a restraining order? It doesn't make sense to me," he said. "I would be laughing out loud."

The school has been cooperating with the FBI and the Los Angeles Joint Terrorism Task Force in investigating the threats. A combined $170,000 reward is being offered for information leading to the arrest and conviction of those responsible.