HOUSTON — Groups representing seed, grain and packaged-food companies formed an organization to stop states from requiring labels on products containing genetically modified ingredients.

The 29 members of the Coalition for Safe Affordable Food include trade groups representing companies such as Pepsico, the world’s largest snack food maker, and Monsanto, the biggest seed company.

The coalition said Thursday it seeks to fend off labeling initiatives like those already approved by voters in Connecticut and Maine, and urged Congress to pass a bill preempting such laws.

Federal legislation should give the Food and Drug Administration sole authority to determine whether genetically modified organisms, or GMOs, pose a health or safety risk in food and need labeling, said Pam G. Bailey, chief executive officer of the Grocery Manufacturers Association. The FDA has repeatedly said labels aren’t needed.

“We want to make it clear to consumers that FDA is looking out for their safety when it comes to GMO technology,” Bailey said Thursday on a conference call with reporters.

Labeling advocates say identifying GMOs is needed so that consumers who distrust the technology can avoid buying food containing those ingredients.

Connecticut and Maine have approved labeling, although those laws don’t take effect until more states follow with their own legislation. While such initiatives have been voted down in California, Oregon and Washington, similar bills are pending in several other state legislatures.

The companies opposing such measures “have failed to win over consumers who overwhelmingly support the mandatory labeling of GMOs, and now they’re trying to steal away consumer choice in congress,” Andrew Kimbrell, executive director for the Center for food Safety, a health and environmental campaign group, said Thursday in an emailed statement.

Opponents of labeling say it will drive up food costs, create a cumbersome patchwork of state laws and confuse consumers by implying a risk they say doesn’t exist.

The anti-labeling coalition will seek a statutory requirement for the FDA to review the safety of all new genetically engineered foods, Cathleen Enright, executive vice president of the Biotechnology Industry Organization, said on the call.

The Biotechnology Industry Organization’s members include seed makers such as Monsanto and DuPont Co. The FDA reviews currently are conducted at the discretion of biotechnology developers.

The coalition said it plans to educate the public about the safety of GMOs. It also said it wants the FDA to set federal standards for voluntary labeling of foods that do or don’t contain engineered ingredients, as well as setting a legal definition for the term “natural” on food and beverage labels.

The group’s 29 members also include the National Corn Growers Association, the National Restaurant Association and the American Beverage Association.