BURLINGAME — A Japanese restaurant that offers exotic meats may have bitten off more than it can chew.

Mokutanya charcoal grill recently added African lion to the menu as a promotional item, and news accounts have generated a swiftly developing backlash on Facebook and other social media sites. Meanwhile, an animal rights advocate, who has investigated how lion meat is produced, said consumers should be wary.

Jason Li, owner of the California Drive restaurant, said he bought 3-4 pounds of lion meat, which he expects will sell out in a week or two. This is only the second time he’s put it on the menu, he said, and he’s not sure if he’ll do it again.

Li said his dealer told him the lion was raised on a farm in Illinois. Other restaurateurs have reportedly given similar accounts of the provenance of their lion meat, but the process by which lions enter the food market is far murkier than that, said Adam Roberts, executive vice president of Born Free USA.

The nonprofit animal rights group concluded a yearlong investigation in 2011 into the supply chain for lion meat. The organization found that most lions that wind up being processed for food are likely exotic pets or captive entertainers that have outlived their usefulness.

“To the best of our knowledge there is no farm where they’re breeding lions for the meat trade,” said Roberts, adding that there is a facility in Illinois that processes lion meat. A growing number of restaurants are offering lion to generate publicity, he said.

Born Free USA also claims there is little federal regulation of lion meat, leading to safety concerns. For instance, consumers have no way of knowing if a given lion had antibiotics in its system when it was slaughtered, Roberts said.

African lions are not listed as endangered species, and federal law does not appear to prohibit their sale for consumption. A proposed law in Illinois would ban processing and selling their meat.

The claim that this lion meat originated in America, as opposed to the wilds of Africa, did little to placate Ken White, president of the Peninsula Humane Society.

“Whether the lion was raised on a farm in Illinois or shot in the Serengeti and immediately put on ice and shipped to the United States, we think it sucks,” said White. “These are animals that we need to treasure.”

Li said putting lion on the menu was in line with his philosophy of giving diners the opportunity for culinary adventure. Mokutanya also offers kangaroo, peacock and alligator in addition to traditional options like chicken and lamb.

A skewer of lion meat costs $70. It has a “very strong, gamy taste,” Li said.

Contact Aaron Kinney at 650-348-4357. Follow him at Twitter.com/kinneytimes.