About 650 jobs will be lost when the plants are closed in Amarillo, Texas; Garden City; and Waterloo Iowa, said company spokesman Rich Jochum. The closures will take effect May 25.

A plant in South Sioux City, Neb., will remain open but run at reduced capacity.

The South Dakota-based company blamed the closures on what it said were unfounded attacks over its lean, finely textured beef. During its processing, bits of beef are heated and treated with a small amount of ammonia to kill bacteria. The filler has been used for years and meets federal food safety standards.

But the company suspended operations in March at the three plants. BPI has declined to discuss financial details, but has said it took a "substantial" hit after social media exploded with worry over the product and an online petition seeking its ouster from schools drew hundreds of thousands of supporters. The U.S. Department of Agriculture has decided that school districts may stop using it, and some retail chains have pulled products containing it from their shelves.

Company officials hoped to recover but have since realized that doing so wasn't possible in the near future, Jochum said Monday. The company paid its workers during the suspension.

"We will continue communicating the benefits of BPI's lean beef, but that process is much more difficult than (countering) the campaign to spread misinformation that brought us to this point," Jochum said in a statement.

State executives who have supported the company blamed what they considered a smear campaign against the product, which has drawn scrutiny even though they and industry officials insist that it's safe.

"This is a sad day for the state of Iowa," said Iowa Gov. Terry Branstad. "The fact that a false, misleading smear campaign can destroy a company's reputation overnight should disturb us all."

The Republican governor said the workers will "go home to their families and will soon be without a job, all because some media on the coasts decided to unfairly and viciously smear the product they so proudly produced."

The phrase "pink slime," coined by a federal microbiologist, has appeared in the media at least since a critical 2009 New York Times report. Celebrity chef Jamie Oliver has railed against it, and it made headlines after McDonald's and other major chains discontinued their use last year.

But a recent piece by The Daily on the USDA's purchase of meat that included "pink slime" for school lunches touched a nerve with a Texas blogger who focuses on kids' food. She started an online petition asking U.S. Agriculture Secretary Tom Vilsack to halt its use in school food, and the USDA will give schools the option of choosing ground beef that doesn't contain it starting in the fall.

Nebraska Gov. Dave Heineman called the plant closings "unfortunate and needless," and said the product BPI produced is safe for consumption.

"BPI is a good family-owned business, and we will continue to work with them in an effort to continue to promote their safe and healthy beef," Heineman said.

Several politicians who toured one of the plants in March - including Branstad, Texas Gov. Rick Perry, Kansas Gov. Sam Brownback, Nebraska Lt. Gov. Rick Sheehy and South Dakota Lt. Gov. Matt Michels - all agreed with the industry view that the beef has been unfairly maligned and mislabeled.