MIAMI—WPP CEO Sir Martin Sorrell again questioned the rationale behind the blockbuster merger of rival holding groups Publicis and Omnicom, at today’s Global PR Summit 2013 in Miami.

Sorrell, in conversation with Cohn & Wolfe CEO Donna Imperato, called the deal “strategically puzzling and structurally clunky.” He also said that “there are regulatory issues…and no benefits articulated for clients or the people within the organization.”

Since the deal was announced in late July, Sorrell has hardly been reticent in airing his views on ‘POG’. At the Summit, the WPP CEO focused specifically on the PR agency implications of the deal.

“From a PR point of view it’s very interesting,” said Sorrell. “One company, Omnicom, I think has a much stronger PR offering. The big battleground here is going to be who controls what.”

“On PR, you would argue, if I was them, it should be run out of New York, or the US, because that’s where the strength in the combined PR operations are,” he added.

Speaking more broadly, Sorrell reiterated his view that Omnicom made the deal “for defensive reasons.”

“I don’t think strategically it made much sense because the two companies are going in opposite directions,” he said. “From our point of view, it’s a big opportunity. There’s already a lot of movement people-wise and a lot of movement client-wise.”

He also questioned whether the merger would secure the necessary approvals. “If this gets through the corporate governance hurdles it will be a miracle.”

Sorrell ruled out making a bid for Interpublic Group, pointing out that current valuations of the latter company “have got ahead of them.”

“If in five years time it was different, who knows?”