Four groups have appealed to the U.S. Justice Department Antitrust Division to investigate the effects of the proposed merger of Microsoft and Yahoo search engines, claiming the partnership creates "significant antitrust concerns, Editor & Publisher reported Monday.

The letter to the Justice Department, from the Center for Digital Democracy, Consumer Action, Consumer Watchdog and U.S. Public Interest Research Group, included specific concern for the Yahoo Newspaper Consortium.

"How will the transaction impact the operation of Yahoo's Newspaper Consortium, which now serves as a revenue source for the beleaguered newspaper industry?" asks the letter to Assistant Attorney General Christine Varney. "The specter of a joint Yahoo and Microsoft-operated Consortium must be evaluated as well for its potential impact on other online publishers."

On July 29, Microsoft and Yahoo formed a partnership that covers significant portions of its search platform business, according to a report by Information Week.

The 10-year agreement will see the Microsoft Bing search engine on all Yahoo sites and have Microsoft retain 12 percent of revenue from Yahoo searches.

The groups requesting the investigation has expressed concern about the use of behavioural advertising by the Yahoo Newspaper Consortium and a tool used by Microsoft, and fear the collaboration could threaten competition and privacy.

The letter requests the Justice Department's antitrust division undertake an investigation into whether the "combination and integration of two powerful sets of data-collection, profiling, and targeting technologies, will this proposed entity be able to unfairly leverage its online ad apparatus to place competitors at a disadvantage." The Microsoft-Yahoo deal is scheduled to close sometime in 2010, according to a Microsoft spokesman.