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Omnicom and Publicis say merger to close by mid-2014 at latest

BARCELONA, Nov 21 (Reuters) - The $35.1 billion tie-up of advertising groups Omnicom and Publicis will close by the middle of next year at the latest, the two groups said on Thursday, pushing the date back slightly later than expected.

Omnicom's Chief Executive John Wren and Publicis boss Maurice Levy said they are still waiting on some regulatory approvals, including Russia and the European Union, which could mean they just miss the original target of closing the deal by the end of March.

"We'll close certainly in the first half and as early as we can," Wren told the Morgan Stanley investor conference in Barcelona, sat next to Levy and being watched by leading competitors, including WPP boss Martin Sorrell.

Once the two groups have been given the green light, the newly formed board will meet to discuss how to return additional earnings to shareholders beyond the already committed dividend payout ratio of 35 percent.

"We have already committed publicly to a dividend of 35 percent ... and that will be done. And when the new board gets together we'll sit down and we'll discuss with the new board how we're going to return the remainder of the earnings to the shareholders, after we've taken care of what our needs are," Wren said.

Omnicom and Publicis, the world's second and third-largest advertising groups respectively, announced their intention to merge in July, saying that they needed to combine to keep pace with technological change and the Internet.

The newly formed U.S. and French company will leapfrog Sorrell's WPP, currently the world's biggest advertising group.

The jumbo deal is rare among the world's "Big Six" advertising groups, which have spent the past few years buying up much smaller businesses in emerging markets and among Web marketing specialists.

If completed, the tie-up will shift the focus to those left standing alone, such as WPP, United States-based Interpublic , France's Havas and Japan's Dentsu.

Wren said the new group would make some acquisitions but not at levels seen in the past. The stance will mean that the group could return more cash to shareholders than has already been committed, he explained on the sidelines of the conference.

"We will not be hoarding cash," he said. "I cannot say more now because it is a board decision."