PORTLAND — Genetically modified sugar beets growing in two fields in Southern Oregon’s Jackson County were destroyed this month in what the FBI called “economic sabotage.”

The agency said in a statement that about 1,000 sugar beet plants were destroyed on June 8, and more than 5,000 plants were destroyed on a different plot three nights later.

Both are owned by a Swiss-based company, Sygenta, the agency said. Calls to the company were not immediately returned.

The statement called the losses significant but said the agency wouldn’t release damage estimates “due to the needs of the investigation.”

FBI spokeswoman Beth Anne Steele wouldn’t say how the crops were destroyed. “We’re not commenting on the specifics because we don’t want to encourage copycats,” she said.