The European Commission extended its probe of the planned purchase of Taylor Nelson Sofres by WPP Group by 10 working days.
WPP, the world's second-largest advertising company, made a $2.2 billion bid in July for TNS, which has responded by urging its shareholders to ignore the offer.
The market research group initially said it preferred to partner with German firm GfK Holdings AG but the German company has since dropped out of the running.
TNS said the WPP offer undervalued the firm and failed to take into account how well the business was performing.
A combination of TNS and WPP's own market research division Kantar would create the world's second-biggest market-research group behind privately held Nielsen.
The new deadline for a decision on the case is Sept. 23. (Reuters)