Google's decision to block the popular web tracking tool cookies is of concern to the US Department of Justice, Reuters reports, citing sources.

A year ago, Google Alphabet Inc announced that it would disallow some cookies in its Chrome browser to improve user privacy. Google has released more details over the past two months, prompting online ad competitors to complain about the loss of its data collection tool.

Four people said questions from DOJ investigators were about how Chrome's policies, including those related to cookies, are affecting the advertising and news industry.

This is a sign that officials are tracking Google's projects in the global online advertising marketplace, where Google and Facebook Inc. control about 54% of income.

One source said executives from more than a dozen companies from a wide variety of sectors spoke with Justice Department investigators.

The government has been investigating Google's search and advertising business since mid-2019 and sued Google last October for using anti-competitive tactics to maintain its search engine dominance.