The World Federation of Advertisers on Monday sent a written protest against the Google-Yahoo ad revenue deal to the European Commission's Directorate-General for Competition.

The protest also has the support of the Association of National Advertisers and the Association of Canadian Advertisers, two of the WFA's member associations. The Association of National Advertisers also sent its own letter protesting the potential Google-Yahoo partnership to assistant attorney general Thomas O. Barnett earlier this month.

"The World Federation of Advertisers (WFA) fears that the proposed advertising alliance between Yahoo and Google will have a detrimental effect on competition, result in price increases and reduce the options available to advertisers worldwide ... Although Google and Yahoo insist this agreement is limited to North America, WFA believes that the effects will be global. One reason for this is that the substantial benefits for both parties in the US and Canada will almost certainly reduce their incentive to compete in other markets as they do today," said the WFA in a statement on its Web site.

The Google-Yahoo deal is also currently under review by the Justice Department for antitrust issues.

The proposed deal would allow Yahoo non-exclusive access to Google's AdSense content, and would allow Google to provide some results for queries on Yahoo's search site. Google and Yahoo would then split the resulting revenue.

Tim Armstrong, Google's president, advertising and commerce, North America, has been blogging in defense of the deal, but some are skeptical of his motives.