The FBI is investigating yet another attack on a university researcher involved in animal experimentation.

A car was burned on Saturday outside the home of the researcher, an associate professor of behavioral neuroscience at the University of California at Los Angeles, an FBI spokesman said. No one was physically injured in the attack, the spokesman said.

A group called the Animal Liberation Front posted a message on its Web site from an entity calling itself the Animal Liberation Brigade claiming responsibility for the arson attack. The statement said the professor “addicts monkeys to methamphetamines and other street drugs” and promised future attacks that cause “a lot more damage than to your property” if the experimentation continues.

UCLA said in a statement that the professor had been investigating treatments for various psychiatric disorders, including schizophrenia, as well as drug addiction. Gene D. Block, UCLA’s chancellor, said in the statement that the university remained committed “to continuing legal and tightly regulated animal research that is critical to the development of treatments and cures for medical conditions.”

“The actions of extremists who use violent and illegal tactics are utterly reprehensible and beyond contempt,” Mr. Block said.

The arson is the latest in a series of such attacks against researchers at UCLA and other colleges. UCLA added another $25,000 to a reward fund as a result of Saturday’s attack. The university has now joined with city and federal agencies to offer a total of $445,000 in rewards for information that will lead investigators to those responsible for five separate attacks.

Other incidents have included arson and vandalism against researchers’ homes and vehicles, and threatening phone calls and e-mail. A court order last year has prohibited the personal information of the researchers from being distributed on Web sites and fliers. Such efforts, however, have not yet led to any arrests, the UCLA student newspaper reported. —Paul Basken