-By Steve McClellan

NEW YORK Agency competitors of WPP have worried for years about possible conflicts of interest arising from the holding company's acquisition of market research assets, such as Millward Brown and Kantar. They've wondered privately if WPP agencies get better pricing for their services.

Similar concerns have also emerged now that WPP is in hot pursuit of Taylor Nelson Sofres, which provides audience measurement, ad tracking and a host of other research services around the world.

The main regulatory hurdle WPP faces is in Europe, where it already provides audience measurement across various media in more than 30 countries. TNS is in the same business and WPP would have to spin off one of its existing operations in order to get an acquisition of TNS approved by the European Union.

But competitors to WPP acknowledge that while they worry about conflicts such as the possibility of the data side of the company deliberately pushing business to the agency side, there is no evidence that conflicts are a reality. "I think Sorrell drives all of his units to generate as much revenue as possible," said an executive at one WPP rival. "But the fear is always there of a conflict of interest." WPP officials couldn't be reached for comment.

An executive at another competitor said that strategically, what WPP can do with its array of research assets is "pull together great deals for clients. It's not so much about cost as it is about the integration of the different products," which might be more difficult to mesh smoothly if they were owned separately.

A senior research executive at one shop outside of WPP said the bigger fear was a Nielsen Co. acquisition of TNS. That's because TNS is working aggressively to develop ratings data from set -top boxes that reveals much more about viewing habits than the Nielsen ratings system. "My fear is that process would slow down if Nielsen were to buy them," the executive said.

Meanwhile, WPP is now putting together a prospectus and other materials for TNS shareholders to consider the WPP offer, which the TNS board has urged them to reject. At the same time, competing researcher GfK is trying to arrange financing for a bid of its own for TNS.