Facebook paused the integration of animated search engine Giphy into its services after United Kingdom regulators opened an antirust investigation into the recent acquisition, according to a source familiar with the matter.

The U.K.’s Competition and Markets Authority (CMA) announced Friday it was looking into whether Facebook’s move “may be expected to result in a substantial lessening of competition within any market or markets in the United Kingdom for goods or services.”

The regulators submitted an official enforcement order on Tuesday.

Australian regulators also opened an antitrust investigation into the deal earlier this week.

The Australian Competition and Consumer Commission said it is looking into whether the deal may give Facebook data that strengthens its market power or harms online messaging rivals — many of which use Giphy.

Facebook’s roughly $400 million acquisition of Giphy has raised antitrust concerns in the U.S. as well.

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Sarah Miller, director of the American Economic Liberties Project, called the deal “just the latest example of the Federal Trade Commission standing by while Facebook and Google centralize control over online communications.”