OWA CITY, Iowa (AP) - When animal rights activists broke into a University of Iowa research lab last fall, overturning equipment, pouring acid on reams of data and releasing more than 300 mice and rats, the damage transcended dollars and cents.

Such attacks on campuses and at private research labs and drug companies nationwide have permanently damaged important research and, some say, helped persuade the next generation of scientists to seek safer careers.

"The financial aspect is the least of our problems," said Richard Bianco, vice president for research at the University of Minnesota, where an attack by vandals in 1999 caused more than $2 million in damage.

"The hardest thing is people see this and don't want to go into science," he said. "Why would they go into science when they can have their work threatened like that?"

At the University of Iowa, four people claiming affiliation with the Animal Liberation Front broke into Spence Laboratories and Seashore Hall in the middle of the night.

Captured on video, their rampage included smashing computers and laboratory equipment, splashing acid on research papers and setting free the rats and mice. They spray-painted "Science not Sadism" on the walls.

In the days that followed, the vandals sent e-mails to media outlets containing names, home telephone numbers and the name of spouses of Psychology Department faculty, students and graduate assistants taking part in research involving animals.

"People here are still intimidated and frightened," said David Skorton, president of the University of Iowa and former vice president of research.

"The irony of it happening here is that, for years, we have exceeded regulations and expectations for managing research involving animals.

"What I do know is this is not going to change our resolve to do animal research here," Skorton said.

Violence by environmental and animal rights extremists is on the rise, so much so that it's been tabbed by the FBI as the top domestic terrorism threat. John Lewis, FBI deputy assistant director for counterterrorism, told executives at a recent national biotechnology conference that the agency has 150 open investigations of arson, bombings and other violence linked to protest of animal use in medical research.

ALF, the Earth Liberation Front and Stop Huntingdon Animal Cruelty are among the top offenders, having claimed credit for many of the more than 1,200 crimes since 1990.

Typical offenses include releasing lab animals, vandalism, arson, property damage and harassing telephone and e-mail campaigns.

In April, ALF claimed responsibility for following the wife of a New York pharmaceutical executive to her job, breaking into her car and stealing a credit card. Offenders used the card to buy $20,000 in travelers checks, split the cash among four charities - then posted a threatening message to the couple on its Web site.

Last month, Peter Daniel Young pleaded not guilty in federal court in Madison, Wis., to domestic terrorism charges alleging he and an accomplice freed more than 7,000 mink from farms in Wisconsin, Iowa and South Dakota in 1997. Prosecutors say the two men acted in the name of ALF and that their actions caused thousands of dollars in damage and stirred fear among the nation's fur farmers.

College campuses also have been a popular target for ALF in the last three decades.

Vandals ransacked labs and caused more than $1 million worth of damage at the University of Minnesota in 1999. An arson fire on the campus of Brigham Young University last year caused $30,000 in damage to a farm building that housed animals used for feed experiments.

Research labs at Louisiana State, Western Washington and the University of California-San Francisco have also been attacked by ALF associates, according to law enforcement.

The University of Iowa attack had a significant impact.

Labs and offices were closed for an average of six weeks and direct financial losses were estimated at $450,000, Skorton said.

That doesn't account for the setbacks in research, he added. Considerable time will be spent catching up.

A longtime vegetarian and student of leaders like Martin Luther King Jr. and Gandhi, Skorton says he rejects the claims of ALF and others that use such teachings to rationalize their behavior.

"That's not civil disobedience. Stand up for what you believe in. This was done in the dark of the night, with ski masks," he said.

"They could be using their energy in other ways to engender a huge debate … on whether there is a better way to get things done. But just going in and trashing a lab is an attempt to put a simple solution on a complex problem."