The European Union announced Tuesday it is once again investigating Google for what could be anti-competitive activities in digital advertising.The investigation will try to determine if Google is harming competitors by restricting third party access to user data that could better target advertising.”We are concerned that Google has made it harder for rival online advertising services to compete in the so-called ad tech stack,” European Competition Commissioner Margrethe Vestager said in a statement.Google said it would cooperate in the investigation.”Thousands of European businesses use our advertising products to reach new customers and fund their websites every single day. They choose them because they’re competitive and effective,” a Google spokesperson said.The EU has fined Google more than $9.5 billion over the past decade for restricting third parties from online shopping, Android phones and online advertising.In the past year, online ads generated $147 billion in revenue for the U.S.-based company.Google’s ad business also is facing scrutiny in the U.S., where several states and the U.S. Justice Department are suing the company for alleged anti-competitive behavior.