OKLAHOMA CITY -- Oklahoma took a step toward allowing livestock owners to slaughter horses for food on Friday when the governor signed a bill that permits the practice, but processing plants must first be authorized by the federal government.

Governor Mary Fallin's action legalized the slaughter of horses so that their meat may be prepared and packaged for export. But slaughterhouses must get U.S. Department of Agriculture authorization, Fallin said.

The slaughter of horses for food had been illegal in Oklahoma since 1963 and was carried out only in Texas and Illinois until Congress stopped it in 2006. The congressional ban was lifted in 2011.

Fallin said horse slaughterhouses in Oklahoma would use more humane practices than those in Mexico because they would be inspected by federal authorities.

Horse meat was at the center of a scandal that erupted in Europe in January, when testing in Ireland revealed that some beef products also contained equine DNA.

The United States Humane Society and animal rights activists opposed the new law in Oklahoma, while livestock interests said the change preserves their private property rights and will benefit horse owners.

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