The Association of National Advertisers sent an official letter to the United States Department of Justice, voicing its concern of the controversial Yahoo-Google search advertising deal reached at the end of July.  

The letter sent to Assistant Attorney General Thomas Barnett included a "comprehensive, independent analysis" of the proposed deal between the two internet giants.  Assuming the DoJ doesn't step in and stop the partnership, Yahoo and Google would essentially control around 90 percent of internet search advertising inventory, which groups such as the ANA believe would throttle fair competition.  

In theory, advertisers are worried that Yahoo will offload its searches to Google and prices will go up once Google controls almost all of the search market.  Google will offer Yahoo advertising services that can be used with Yahoo's search engine and other online services. 

The ANA is made up of more than 400 companies that invest at least $100 billion in marketing and advertising, internal ANA numbers indicate.

Google wants to begin the agreement with Yahoo sometime next month, even though the deal remains under heavy scrutiny by the DoJ, Google Chief Executive Officer Eric Schmidt said in an interview in August.  Both Google and Yahoo offered to give the government three and a half months to evaluate the deal, even though that legally wasn't necessary.

Both search engine giants said prices would be determined by the advertisers and not between Yahoo and Google, but a large portion of the advertising industry still is not convinced.  Not surprisingly, Microsoft has also been an outspoken critic of the deal, stating that there is a strong possibility of a Yahoo-Google monopoly.  The deal is effective for the United States and Canada only, with both companies declining to mention if the deal could go international at a later date.

The Justice Department is expected to announce in the next few weeks if it will try and block the Yahoo-Google deal, and to what extent it wishes to do so.