SAN FRANCISCO, California (Reuters) -- California Attorney General Bill Lockyer has filed a lawsuit to force top makers of potato chips and french fries to warn consumers about a potential cancer-causing chemical found in the popular snacks.

In a complaint filed Friday in Los Angeles Superior Court, Lockyer sought an injunction to stop restaurant chains such as McDonald's Corp. and Wendy's International Inc. from selling french fries without some form of warning.

Also named were producers of potato chips and other packaged potato products like PepsiCo's Frito-Lay Inc. and Procter & Gamble Co., makers of Pringles chips.

The suit asks manufacturers of these products to identify the dangers of high levels of acrylamide, a chemical that studies have found is created when starchy foods are cooked at high heat.

"I know from personal experience that, while these snacks may not be a necessary part of a healthy diet, they sure taste good," Lockyer said in a statement. "But I, and all consumers, should have the information we need to make informed decisions about the food we eat."

The lawsuit alleges that companies have violated a state law passed in 1986 requiring companies to provide warnings before exposing people to known carcinogens or reproductive toxins.

In 2002, scientists found potatoes and other starchy foods cooked at high temperatures contained low levels of acrylamide. Other studies have discounted the potential toxicity of acrylamide to humans.