Italy's Luxottica and France's Essilor merged last October to create the world's biggest producer of spectacles and lenses. Analysts say the division of power at the group is unclear and that tensions could undermine the integration process.

The group has just launched the search for a new chief executive, to be appointed by the end of next year.

Leonardo Del Vecchio, the founder of Luxottica who is now the largest shareholder and the executive chairman of the combined group, had appeared to indicate in November that he wanted his right-hand man Francesco Milleri to get the CEO job - a prospect that has irked the French side.

On Wednesday, a spokesman for Del Vecchio, 83, said his November comments "shouldn't be interpreted as his desire to appoint Francesco Milleri as CEO of EssilorLuxottica."

The spokesman added that Del Vecchio, who has 32 percent of EssilorLuxottica, wanted to transfer some operational functions to Milleri, so that he could focus more on strategic matters.

The governance issue came back into focus on Wednesday after a Financial Times report said the French and Italian sides were pushing their own candidates for the top job.

Milleri started off as an IT consultant to Luxottica and grew closer to Del Vecchio over the years, eventually becoming the billionaire founder's most trusted aide and CEO of the Italian company.

The spokesman said giving additional powers to Milleri now would not alter the balance of power with the French side of the group and would not affect the search for the new CEO. Under the terms of the merger, Del Vecchio and Essilor CEO Hubert Sagnieres are sharing powers for the first three years.

"(Del Vecchio's holding) Delfin wants to respect all the merger agreements," the spokesman said.

An Essilor spokesman said Del Vecchio's gesture was not addressed by the merger agreement of the two companies.

"Delegation of such power by the executive chairman alone is not addressed specifically in the business combination agreement without the agreement of the executive vice chairman," the spokesman said in an emailed statement.

"Only the EssilorLuxottica board will decide on the key executives including the CEO. A unilateral nomination by the executive chairman is a sign of a takeover with no premium to shareholders of Essilor," he added.

Analysts said the group should urgently define a clear leadership.

"It is essential for the execution of the plan. We think this should be a priority and cannot wait until 2020," analysts at broker Equita said in a note.

Two sources close to Essilor said EssilorLuxottica would hold a board meeting to address governance issues among other merger-related topics on March 18.

(Reporting by Claudia Cristoferi in Milan, Matthias Blamont in Paris; Editing by Keith Weir and David Evans)

By Claudia Cristoferi and Matthias Blamont