Instagram “influencers” largely ignore Federal Trade Commission (FTC) warnings about stealth advertising, according to a report.

Despite the FTC’s warning to brands about stealth advertising in April, celebrities and other “influencers” still reportedly advertise products without notifying fans of their connection to the brand.

A “coalition of consumer advocates” discovered a list of influencers already warned through a Freedom of Information Act request before launching an investigation to see if they were now following the FTC’s regulations.

“Though the warnings involved bona fide celebrities like Luke Bryan, Sean ‘Diddy/Puff Daddy/P. Diddy’ Combs, Naomi Campbell, Sofia Vergara, Heidi Klum, Victoria Beckham, and lots of people who were briefly well-known for acting like idiots on reality TV, the letters were sent to the various cosmetics, apparel, beverage, and electronics companies that had apparently compensated these people,” reported Consumerist on Monday. “The letters reminded the brands that Instagram posts must adequately disclose any ‘material connection’ between an advertiser and an influencer, and that these disclosures be ‘clear’ and ‘conspicuous.'”

“Merely burying ‘#ad’ among multiple other hashtags is not sufficient. The same goes for a disclosure at the end of a very long caption that is automatically truncated by the Instagram app,” they continued. “While the letters didn’t go directly to the Instagram influencers, one might hope and/or assume that warning recipients — including brands like Adidas, Chanel, Dunkin’ Donuts, Puma, and Popeyes — would pass this concern on to the celebrities who stealth-advertised their products.”

Consumerist reports a coalition of the groups Public Citizen, Campaign for a Commercial-Free Childhood, and Center for Digital Democracy found “nearly every single one of the influencers identified in the warning letters continued to post Instagram ads without proper disclosures.”

Over a six-week investigation, the coalition discovered that 327 out of 412 posts from 47 influencers failed to abide by the FTC’s rules.

These posts included photographs of models such as Naomi Campbell and Amber Rose, who displayed and recommended products from companies that were compensating them.

According to Consumerist, the FTC currently reviews the results of the investigation.

Charlie Nash is a reporter for Breitbart Tech. You can follow him on Twitter @MrNashington or like his page at Facebook.