Martin Schulz, the center-left's candidate to lead the European Commission after EU parliamentary elections this month, has joined calls for Google's market dominance to be subject to strict regulation.
Two days ago Germany's Economy Minister Sigmar Gabriel said a ruling by a top European court on Tuesday that Internet firms can be made to remove irrelevant or excessive personal information from the web was a "wake up" call for digital safeguards.
Germany was considering if firms such as Google were abusing their market leader position he said. Google has declined to comment.
"Whoever knows everything about citizens, firms and politicians achieves a level of power which doesn't belong in a pluralistic democracy," Schulz, who is president of the European parliament, told Reuters in Berlin.
Besides concerns about what data it displays, the world's top Internet search engine Google has also faced difficulties over anti-trust issues and how it shows competitors' information.
Google reached a deal with EU antitrust chief Joaquin Almunia in February by agreeing to display rivals' links more prominently, hoping to end a three-year-old case that could have led to a fine of up to $5 billion (3.6 billion euros).
Rivals say Google's concessions do not go far enough and will only entrench its dominance of Internet searches. EU regulators plan to issue a final decision after the summer break.
(Reporting by Holger Hansen, writing by Alexandra Hudson, editing by William Hardy)