U.S. antitrust agencies should block Google's proposed acquisition of crowdsourced mapping app Waze because the deal would take away Google's major competitor in mobile maps, consumer group Consumer Watchdog said.

Google's proposed acquisition [1] would remove the most "viable" competitor to Google Maps on mobile devices, Consumer Watchdog, a frequent critic of Google, said in Wednesday letters [2] to the U.S. Department of Justice and the U.S. Federal Trade Commission.

"Google already dominates the online mapping business with Google Maps," wrote John Simpson, Consumer Watchdog's Privacy Project director. "The Internet giant was able to muscle its way to dominance by unfairly favoring its own service ahead of such competitors as Mapquest in its online search results."

The acquisition will also "allow Google access to even more data about online activity in a way that will increase its dominant position on the Internet," Simpson added.

A Google spokeswoman didn't immediately respond to a request for comment on the Consumer Watchdog letters.

Last May, at the All Things Digital conference, Waze CEO Noam Bardin described Google as his company's main competitor. "What search is for the Web, maps are for mobile," he said then [5], as quoted on Forbes.com. "We feel that we're the only reasonable competition to [Google] in this market of creating maps that are really geared for mobile, for real-time, for consumers — for the new world that we're moving into."

The DOJ and the FTC should consider those comments, Simpson wrote.

"You should take Bardin at his word," he said. "Approval of the Waze deal can only allow Google to remove any meaningful competition from the market. It will hurt consumers and hinder technological innovation."

Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's e-mail address is [email protected].