Speaking during an interview on Bloomberg Television on Wednesday (May 23), Levy refused to specify what those difficulties were.
Publicis, the world's fifth-largest advertising group, wants to double the size of its media-buying unit Optimedia by merging it with Zenith. However, this would demote Cordiant to minority shareholder status in the enlarged media buying company with a stake of around 25%. It currently owns 50% of Zenith.
A merger between Optimedia and Zenith would give the agency much greater buying power by allowing it to demand lower rates from media owners and, in turn, offer clients a better deal. Paris-based Publicis obtained the stake in Zenith when it bought Saatchi & Saatchi for $1.9bn (£1.3bn) in September 2000.
Initially, the talks were reported to be close to a deal in December, but the negotiation period was extended until March. Levy refused to name an end date for the talks. He added that both companies were agreed on the value of the combined business and its management.
According to Levy, the combined group will have $16bn (£11.3bn) in billings and be the fourth-largest media-buying company. Shares in Cordiant recovered slightly yesterday from the day before's fall of 1.5p with a rise of 0.5p to 254.5p.