But agriculture officials played down the risk to humans after Hallmark/Westland Meat Packing agreed to take back more than 143 million pounds of raw and frozen meet when it was found in violation of inspection rules.

The company, based in Chino, California, voluntarily recalled the beef after the federal Food Safety Inspection Service (FSIS) determined the cattle "did not receive complete and proper inspection."

The company did not "consistently contact the FSIS public health veterinarian in situations in which cattle became non-ambulatory" before being slaughtered, the USDA statement said Sunday.

Federal rules usually ban the slaughter of "downer cattle" -- those unable to walk -- as a safeguard against mad cow disease or bovine spongiform encephalopathy (BSE).

US Secretary of Agriculture Ed Schafer said Hallmark/Westland had been suspended by the FSIS, and that the federal government had suspended food and nutrition contracts with the company.

"I am dismayed by the inhumane handling of cattle that resulted in the violation of food safety regulations" by the company, Schafer said in a statement.

"It is extremely unlikely that these animals were at risk for BSE because of the multiple safeguards; however this action is necessary because plant procedures violated USDA regulations," he added.

The department did not say where those food products had been sold, but schools in Washington state and California removed beef from their lunch menus as a precaution, local officials said.