Animal rights activists on Wednesday protested at a San Francisco Costco store and projected video of pigs dying in a Southern California slaughterhouse.

The activists, with Direct Action Everywhere, are calling on Costco to drop Smithfield Foods—the world's largest pork producer—as a supplier.

The video was recorded secretly after an activist planted cameras inside a pit at the Farmer John slaughterhouse in Vernon, owned by Smithfield Foods. The footage shows pigs thrashing as they are gassed with carbon dioxide.

Activists maintain the company is violating the Humane Slaughter Act, a federal law that aims to decrease the suffering of livestock during slaughter.

While the footage was projected onto the Costco Wholesale store, located on 10th Street in the city's SoMa neighborhood, audio played of the pigs screaming through speakers across the street.

Jim Monroe, vice president of corporate affairs at Smithfield Foods, denied the claims that the company violated federal law.

"We adhere to all humane handling and stunning regulations for livestock with the oversight of the United States Department of Agriculture Food Safety and Inspection Service," Monroe said in a written statement Thursday morning.

"[M]any other authorities on animal health recognize carbon dioxide stunning as a humane stunning method for food animals. Carbon dioxide stunning quickly renders hogs into a state of analgesia."

Direct Action Everywhere is an international animal rights network based in Berkeley. This is not their first protest at Costco. In November, the organization staged a protest over the wholesaler's continued use of Smithfield after two Bay Area activists were acquitted of felony charges for taking piglets from a farm.