German Vice Chancellor Sigmar Gabriel has said he was worried the market power of firms like Google was hurting competition on the Internet.
Gabriel, who is also economy minister, has repeatedly voiced concern about the dominance of U.S. software companies and last year suggested firms like Google should be broken up if they abuse dominant market positions.
"How can it be that in order to have Google's (mobile operating system) Android you need to pre-install Google Search, Google Browser, Google Mail, Google You-Tube and its app store on the device?" Gabriel said at an event in Berlin.
He welcomed a decision by the European Commission in April to launch an antitrust investigation into Google's Android system over concerns anticompetitive constraints imposed by the company were hampering markets.
Gabriel said agreements needed to be reviewed to ensure that customers were not being barred from using competing browsers and web services and locked into "Google Internet".
Market power should not just refer to individual services but should also be assessed according to the value chain on the Internet, he added.
In Germany, fears of digital domination by firms like Google are linked with wider concerns of U.S. cyber espionage since the revelations in 2013 of mass U.S. surveillance on German citizens.
A report published on Monday by the Monopolies Commission, which advises the government, advised against the need for special regulation regarding the provision of Internet search and instead recommended adjusting existing competition law.