Google is facing yet more antitrust issues, with the Japan Fair Trade Commission opening an investigation.

According to CNBC, Japan Fair Trade Commission announced it would open a probe into the search giant over antitrust concerns related to how it operates its search on mobile devices. In particular, the regulator wants to determine if Google pressured smartphone makers not to include rival search engines on their devices in exchange for a share of Google’s ad revenue.

Google denied that it had engaged in any wrongdoing in a statement to the outlet.

“Its openness and flexibility ensure that users always have a choice to customize their devices to suit their needs, including the way they browse and search the internet, or download apps,” a company spokesperson told CNBC.

Google is already facing multiple challenges to its business, including a high-stakes antitrust trial in the US that could have profound implications for the company.