Many upscale restaurants and gourmet grocery stores in Chicago continue to sell foie gras, five months after the city banned the sale of the liver delicacy.

Some restaurants are listing foie gras openly on their menus. One restaurant has found a loophole in the ban, serving the dish as a complementary addition. Rumours have circulated that one establishment is selling the controversial dish to patrons who know the secret password and ask for the "special lobster."

Foie gras, a French delicacy, is made from the livers of ducks and geese that have been force-fed. The practice makes the livers expand and soften. Animal rights activists have long said the overfeeding is inhumane.

City officials say they've issued warnings to some restaurants and stores, but haven't yet laid any fines because they've been too busy addressing other health issues.

"We need to focus as much as possible on things that actually make people sick and kill people," said Health Department spokesman Tim Hadac. "Our mission is to protect human health and not the health of geese and ducks."

But animal rights activist Gene Baur, of Farm Sanctuary, says he believes the ban has been largely effective.

"Our supporters are going into restaurants and we're told that they are not selling foie gras," Baur said.

Ald. Joe Moore proposed the ban in 2005, saying force-feeding birds amounts to torture. The U.S. Humane Society supported the proposal and launched a campaign urging Chicago residents to contact their aldermen.

The society said the caged ducks and geese experience bruising, lacerations, sores and organ ruptures. The council passed the ordinance banning the sale of foie gras in April.

More than a dozen countries including the U.K., Denmark, Finland, Germany, Israel, Norway, Poland, Sweden and Switzerland have introduced legislation on the production and sale of foie gras.

With files from the Associated Press