Google is reportedly facing a new round of European Union questions about its Android operating system for mobile devices as as regulators quizzed rivals over applications for maps, e-mail and other services. The EU wants to know whether Google Maps for phones has supplanted portable or in-car navigation devices, such as those produced by TomTom NV and the HERE unit of Nokia Oyj, according to a document sent to companies and "seen" by Bloomberg.

Officials are also seeking data, such as user numbers, about downloaded or pre-installed mapping apps on devices, as well as costs mapmakers face to produce a mobile-ready app.

Google has been the target of a five-year antitrust investigation into its search services. The EU accused the tech company earlier this year of positioning and displaying its own comparison-shopping service above rivals in its general search.

Margrethe Vestager, the EU’s antitrust chief, said Monday that officials are "still in the middle of things" with their Android probe and are analyzing Google’s "data-intensive" response to the charges on the shopping case.