Two researchers have been convicted of plotting to sell stolen pharmaceutical formulas valued at more than $1 billion in what authorities described as U.S. history's largest industrial espionage case.

The two were found guilty in federal court Friday of trying to sell patented trade secrets on the anti-viral and promising anti-cancer drug interferon and Ivermectin, an anti-parasitic drug describred as the leading animal health product in the world.Bernard Mayles, 52, had spirited the secrets from the companies he worked for, including pharmaceutical giant Merck and Co., and then passed them on to Mario Miscio, 63, Assistant U.S. Attorney Kevin McKenna said.

Mayles and Miscio planned to sell the secrets to an undercover FBI agent posing as an international businessman who offered the pair millions of dollars for the formula. The agent said he wanted to market the drugs in Eastern Europe.

The FBI became involved after one of the pharmaceutical firms alerted federal authorities that trade secrets may have been stolen.

The two were caught last August in Atlanta as they handed over to the agent a folder full of documents and two test tubes containing micro-organisms needed to manufacture the drugs.

Mayles worked as a senior research director at Merck and later became a section leader for Schering-Plough Corp. before becoming affiliated with Miscio's Biopharm Research Inc., of Hazlet, N.J., in 1987.

Mayles was directly involved in the development of Ivermectin at Merck's Rahway laboratory and in the research into interferon at Schering's Bloomfield facility, McKenna said.

Ivermectin has been used to treat parasite-induced river blindness in humans in rain forests, as well as in treating animals suffering from parasitic diseases.

The drug interferon has been used to treat hepatitis and has shown some effectiveness in treating certain forms of cancer.