Army experts conducted tests today on several vials of a substance that FBI agents said is deadly anthrax seized from a local businessman and a self-styled germ warfare expert with links to the white supremacist movement.

Attorneys for the two suspects said the impounded substance is a legal anthrax vaccine that is readily available for inoculation of farm animals. But authorities cautioned it may not be known until next week whether, as they warned after seizing the substance Wednesday evening, the vials contain an anthrax culture of a kind that could be used for biological warfare or terrorism.

The substance was being tested at the Army's Medical Research Institute of Infectious Diseases at Fort Detrick in Frederick, Md., the FBI said in Washington.

Larry Wayne Harris, a microbiologist on probation for fraudulently obtaining bubonic plague toxins in Ohio in 1995, and William J. Leavitt, a Las Vegas area entrepreneur and home-laboratory medical researcher, were arrested Wednesday outside a suburban Las Vegas professional building in which Leavitt had laboratory equipment that he leased to a doctor. The two were charged Thursday with possessing anthrax for use as a weapon.

The head of the Las Vegas FBI office, Bobby Siller, said they "posed a potential chemical and biological threat to our community" and had bragged about possessing enough anthrax to wipe out entire cities.

But Leavitt's attorney, Lamond Mills, said that when his client was arrested he was "bringing the kind of anthrax vaccine that you give to animals. We believe that it was vaccine-grade and not harmful to anybody." Mills said Leavitt and Harris had the vaccine because they were negotiating to buy equipment they believed they could adapt to combat viral and bacterial diseases and wanted to test it before putting up any money.

Kirby Wells, a Las Vegas civil attorney, said he represented Leavitt in negotiations in which Leavitt was to buy, for $2 million, laboratory equipment that he hoped could be used to "neutralize" deadly biological agents like anthrax. Wells identified the seller as Ronald G. Rockwell, who describes himself as an engineer and who Wells said tipped the FBI that Harris and Leavitt possessed "weapons grade" anthrax. The FBI criminal complaint says Rockwell has 1981 and 1982 convictions for conspiracy to commit extortion.

Rockwell was not identified by name as the informant in a criminal complaint released Thursday after the two suspects were arraigned on charges of possessing anthrax and conspiring to possess it.

Wells, in an interview, described Leavitt, 47, as an entrepreneur who owns a fire protection company and conducts alternative medical research in a laboratory at his home in suburban Logandale. The lawyer said that for more than a year Leavitt has been experimenting with a machine that he hoped would cleanse viruses from blood and cure numerous diseases, including AIDS. It was for that purpose, Wells said, that Leavitt asked Harris, whom he knew by reputation, to fly to Las Vegas as a consultant and help test the machine. If the device worked, Rockwell was to be paid up to $18 million more in royalties, Wells said. He said Harris told Leavitt he had vials of anthrax vaccine that could conclusively determine the efficacy of the equipment Rockwell was offering to sell.

"Instead of showing up with the equipment, Rockwell blew the whistle and told the FBI that they had weapons-grade anthrax. It wasn't weapons grade, it was vaccine, and I'm hoping this will all turn out to be a tempest in a teapot," Wells said.

Rockwell could not be reached today, and his attorney, Ernest Roark III, did not return telephone calls.

Dan Royal, an osteopath whose office is in the professional building where Harris and Leavitt were arrested, said in an interview that he leased medical equipment from one of Leavitt's businesses and that he and Leavitt were collaborators on a research project for patients with immunity deficiencies.

Royal confirmed that FBI agents seized a cooler containing wrapped petri dishes from his office, which he said had been delivered Wednesday. But he said he did not order the materials and assumed they were delivered by mistake. He described the petri dishes as "harmless" and in their original factory packaging without any sign of use.

The FBI, in its affidavit, said its informant told agents he saw Leavitt carry the cooler into Royal's office and then remove two items.

Harris, 46, is a microbiology graduate of Ohio State University and a former well tester whose anti-Semitic and anti-black ardor as a member of the white supremacist groups Aryan Nation and Christian Identity Church evolved sometime in 1993 into an obsession with what he believed to be the certainty of global annihilation from biological warfare.

By his own account, related in a series of taped interviews he gave to a Christian and family values television station here the day before his arrest Wednesday night, Harris's entry into the fringe of free-lance biological warfare research began when he met an Iraqi student at Ohio State who told him that Iraq was planning to unleash deadly biological agents in the United States in retaliation for its defeat in the 1991 Persian Gulf War.

The videotapes of the interview with KKJK-TV's Ted Gunderson, a retired FBI agent who hosts a show that explores various conspiracy theories, were seized by FBI agents yesterday. But Doc McKay, the station's general manager, stated in an interview that Harris had said the Iraqi student told him that hundreds of Iraqi women had infiltrated the United States carrying vials of anthrax and other biological warfare agents in their body cavities.

Two years after his claimed meeting with the Iraqi woman at Ohio State, Harris, who is a registered microbiologist with the American Society of Microbiology, was inspecting wells and septic tanks for bacteria as an employee of a Dublin, Ohio, well-testing company. He was also beginning to dabble in experiments he said he hoped would lead to a way of countering biological warfare.

Authorities say Harris used his state certification for the well-testing job to obtain three vials of inactive bubonic plague from a Maryland laboratory. He was charged with wire fraud and sentenced in 1995 to 18 months' probation for illegally obtaining the substance.

A year later, Harris published a 131-page book, "Bacteriological Warfare: A Major Threat to North America," in which he describes his meeting with the Iraqi woman and warns of an imminent danger of a biological attack that would kill 180 million people. In the book and in lectures to promote it, he explained in detail how weapons-grade plague and anthrax are made and how people can survive using antibiotics.

According to an FBI affidavit filed with the criminal complaint Thursday, Harris once told an unidentified group about a vague conspiracy to plant bubonic plague toxins on New York City subway tracks in an attack that would kill hundreds of thousands of people and cripple the economy.

Harris said after his 1995 arrest that the plague vaccine he purchased was inactive and, therefore, harmless, and that he ordered it simply to aid research for his book. He also said he hoped it could be used for experimentation that would lead to the discovery of an effective antidote to bubonic plague that he feared would be unleashed in a biological attack -- an explanation that mirrors accounts given by attorneys for Harris and Leavitt of why they were in possession of anthrax vaccine when arrested here Wednesday night. Staff Writer Roberto Suro in Washington contributed to this report. CAPTION: FBI agents arrive Thursday at the Lancaster, Ohio, home of microbiologist Larry Wayne Harris, one of two men charged with possessing anthrax for use as a weapon. Carol Harris, the suspect's wife, is opening the door.