Adds Walmart statement, paragraph 7

By Jonathan Stempel

July 8 (Reuters) - The U.S. Federal Trade Commission on Tuesday called on Amazon.com AMZN.O and Walmart WMT.N to crack down on third-party sellers that make deceptive "Made in USA" claims on the retailing giants' online marketplaces.

In letters to Amazon and Walmart, the FTC said it had learned of several instances where third-party sellers falsely claimed their products were made in the United States.

The FTC urged both companies to take "corrective action" against sellers whose "Made in USA" claims violate federal law and Amazon's and Walmart's codes of conduct.

Four smaller retailers also received FTC warning letters demanding they cease "Made in USA" claims unless they prove "all or virtually all" of the products in question are made domestically.

The four retailers are Oak Street Bootmakers in Chicago; Stand Flag Poles in Fort Lauderdale, Florida; football equipment maker Pro Sports Pads in Jacksonville, Florida, and medical products maker USA Big Mountain Paper, also in Jacksonville.

"Consumers want to have confidence that when they buy something labeled 'Made in the USA' they are actually supporting American workers and the American economy," FTC Chairman Andrew Ferguson said in a statement.

Walmart said in a statement it has "zero tolerance for noncompliant products from third-party sellers," and upon identifying those products has them removed.

Amazon did not immediately respond to requests for comment.

Pro Sports Pads CEO Joshua Baker said his company complies with labeling laws, and sent the FTC proof it makes Pro Gear Custom shoulder pads in Jacksonville from domestic materials.

The other companies did not immediately respond to requests for comment.

Many companies have been accused by regulators or in private lawsuits of using imprecise labeling to induce shoppers to pay more, including through appeals to their patriotism.

In 2021, the FTC adopted a "Made in USA Labeling Rule" to protect businesses and consumers.

The agency later brought cases against kitchenware and home furnishings retailer Williams-Sonoma and Pyrex kitchenware maker Instant Brands, and said it obtained $15.8 million of judgments in 11 "Made in USA" enforcement actions between 2021 and 2024.

(Reporting by Jonathan Stempel in New York; Editing by Chizu Nomiyama, Sonali Paul and Marguerita Choy)

((jon.stempel@thomsonreuters.com; +1 646 223 6317; Reuters Messaging: jon.stempel.thomsonreuters.com@reuters.net/))