Chipotle Mexican Grill is facing a class action lawsuit saying the chain's marketing is misleading and deceptive because a solid portion of the food it sells is made with genetically modified ingredients (GMOs).

Filed in California, the complaint challenges the chain's assertions, starting with April's "Food With Integrity" campaign, which claimed bragging rights on becoming the first major restaurant in the U.S. to serve foods free of GMOs, according to the New York Daily News.

However, on the company website, there are disclaimers that outline what products sold at the restaurant are unavoidably not GMO-free, such as soft drinks. The feed eaten by animals that end up in Chipotle food was unlikely to be free of GMOs, as well, the site says:

"The meat and dairy products we buy come from animals that are not genetically modified. But it is important to note that most animal feed in the U.S. is genetically modified, which means that the meat and dairy served at Chipotle are likely to come from animals given at least some GMO feed. We are working hard on this challenge, and have made substantial progress: for example, the 100% grass-fed beef served in many Chipotle restaurants was not fed GMO grain - or any grain, for that matter."

"Many of the beverages sold in our restaurants contain genetically modified ingredients, including those containing high fructose corn syrup, which is almost always made from GMO corn."

The lawsuit, filed by California resident Colleen Gallagher on Friday, alleges that Chipotle has violated the Federal Food, Drug and Cosmetic Act - which bans false advertising on food labels - and that the restaurant has tricked customers into paying more by claiming its GMO free.

The law firm issued a statement attributed to attorney Laurence D. King that read in part: "Chipotle's advertising in its stores should have accurately informed customers about the source and quality of its ingredients and should not mislead consumers that they are serving food without GMOs when in fact they are," according to Fortune.

Gallagher says that customers are not likely to see the disclaimers and will only know about the company through advertising.

"Chipotle only discloses this information on its website because it knows its fast-food customers never need to visit Chipotle's website to buy food," the suit states.

Chipotle spokesman Chris Arnold didn't discuss details of the lawsuit, but said "we do plan to contest this."