James Martin/CNET

The top antitrust official at the Department of Justice has removed himself from an investigation into alleged anticompetitive practices at Google. Makan Delrahim, assistant attorney general for the Justice Department's antitrust division, has recused himself due to a potential conflict of interest. The decision was earlier reported by The New York Times.

"As the technology review progressed, Assistant Attorney General Makan Delrahim revisited potential conflicts with previous work with the Department of Justice's ethics office," said a DOJ spokesman in an emailed statement Tuesday. "He and the ethics office have decided that he should now recuse himself from a matter within the tech review in an abundance of caution."

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Google is facing a wave of regulatory scrutiny. Last September, a large group of state attorneys general announced an antitrust probe into the search giant. In July, the Justice Department announced an antitrust probe into the tech industry more broadly, targeting Google, Apple, Facebook and Amazon. And in June, House Democrats announced their own investigation into tech giants, meant to explore whether the companies are engaging in "anti-competitive conduct."

While working for a private law practice in 2007, Delrahim was reportedly involved with lobbying for Google's acquisition of ad firm DoubleClick, according to the Times.

Google's online ad tools, largely built around the DoubleClick acquisition, are becoming a major focus of the Justice Department investigation, according to a report Wednesday from The Wall Street Journal. The DOJ has reportedly reached out to more than a dozen companies as part of its probe, including "publishers, advertising technology firms and advertising agencies."

Associate Deputy Attorney General Ryan Shores will continue to oversee the tech review, said the DOJ spokesman, with assistance from Deputy Assistant Attorney General Alex Okuliar.

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Originally published Feb. 4, 7:13 a.m. PT.

Update, 9:45 a.m.: Adds comment from Department of Justice.

Update, Feb. 5: Adds more details on the Justice Department probe.