A U.S. consumer advocacy group has written to the European Commission asking it to block Google's deal to acquire Motorola and to launch an investigation into the Internet giant's alleged anticompetitive behavior.

The Commission is expected to approve Google's takeover of Motorola Mobility for $12.5 billion by mid-February, after requesting and receiving additional information from Google. But Consumer Watchdog, an independent consumer rights organization that has in the past worked with Microsoft, believes this would be bad for consumers on both sides of the Atlantic.

"Google's Android smartphone operating system dominates the mobile market with a 38 percent share and is growing," said John M. Simpson, Consumer Watchdog's privacy project director, in a letter to European Competition Commissioner Joaquin Almunia.

"Google controls 95 percent of the mobile search market. There is evidence it is pressuring handset manufacturers to favor Google applications when using the Android operating system," Simpson added. "Allowing the Motorola Mobility deal would provide Google with unprecedented dominance in virtually all aspects of the mobile world - manufacturing, operating systems, search and advertising. It would be a virtually unstoppable juggernaut."

According to reports, the takeover would give Google access to more than 17,000 Motorola patents. "If Google is allowed to dominate the mobile market it will result in higher prices for consumers and stifle innovation," said Simpson.

But he went further, urging the Commission to launch a formal antitrust investigation into Google's search activities. The Commission is already considering complaints from competitors and is likely to make a decision on that by the end of March.

Google has more than 90 percent of search in some markets compared to about 65 percent in the U.S.

Among the actions that Consumer Watchdog wants the Commission to consider are significant financial penalties, transparency on how Google's "quality score" is derived and forcing Google to break up into different companies "so there is no incentive to unfairly use search to promote other services."

It seems unlikely that the Commission would go that far, but it can fine companies up to 10 percent of their global turnover for breaching European Union rules, IDG News Service reported.