Although Martin Sorrell's marketing services company did not disclose the content of the "information," it said it believes the new material will support its attempts to invoke the "material adverse change" condition in its original offer, which values Tempus at $639 million. WPP executives were not available for comment.
WPP's statement came as the U.K. Takeover Panel continues to look at the holding company's claims to pull out of the deal.
The panel's ruling, which is widely believed to go against WPP, is expected this week.
The European Commission on Monday cleared the way for the takeover after the EC's taskforce on mergers said the acquisition would not affect competition for marketing communication services or media buying companies in those markets the deal would reach.
The EC said WPP's market share would be less than 15% for all marketing and advertising services in the European Economic Area. Even though in certain markets, such as Italy, the Netherlands and Sweden, WPP's share would be between 15% and 25%, the merged group would nevertheless face stiff competition, the EC said.
WPP, which also announced its offer had been extended to Oct. 29, is to issue a third-quarter trading statement Thursday.