Over the weekend, executives from Yelp and TripAdvisor tweeted that Google searches on smartphones for their businesses buried their results beneath those of Google's own services. Google claims it's due to a code bug, which it's working to fix.

CEO and co-founder of Yelp, Jeremy Stoppelman, isn't convinced by the 'bug' excuse. He demonstrated on Twitter how searching for "yelp Ozumo" (a Japanese restaurant in San Francisco) on a smartphone pushed Google's OneBox results, including a map and customer reviews, to the top of the results. "Far from a glitch, this is a pattern of behavior by Google," Stoppelman told Re/Code.

Stoppelman also showed how searches for "TripAdvisor Hilton" were also leading with Google's results, prompting TripAdvisor CEO Stephen Kaufer to join in the conversation. "Gimme a break, @google. Search for "tripadvisor hilton" puts the tripadvisor link so far down you can't see it," he tweeted.

On Tuesday, a Google Spokeswoman told Re/Code: "The issues cited were caused by a recent code push, which we're working quickly to fix," but many have questioned if this really is the case. Travis Katz, CEO of local search firm Gogobot, pointed out that both his company and Foursquare weren't affected by the issues. He tweeted that it's "unlikely this is a bug." Stoppleman was equally dubious about Google's excuse, adding that the company was "about as truthful as Trump."

Both Yelp and TripAdvisor are complainants in the European Union case against Google for anticompetitive behavior. Their complaints center on exactly what Google appears to be doing in this instance: unfairly and intentionally promoting its own products in search results over others.

Yelp has long accused Google of manipulating searches. "The easy and widely disseminated argument that Google's universal search always serves users and merchants is demonstrably false," it argued in a dossier released this summer. "Instead, in the largest category of search (local intent-­based), Google appears to be strategically deploying universal search in a way that degrades the product so as to slow and exclude challengers to its dominant search paradigm."

During the FTC antitrust investigation of Google, the Wall Street Journal dug up internal documents that revealed the company's use of "co-occurrence signals." When searches triggered competing websites to rise, Google's algorithm automatically surfaced its own products.

Yesterday, Kaufer said in a statement: "It's clear that Google continues to seek ways to manipulate its search results to benefit Google's own interests. Google's behavior to suppress the most useful and relevant content is both deceptive and anti-consumer."