CMA CGM's boss, billionaire Rodolphe Saade, told France Inter radio station last month that he was ready to expand investments in French media assets beyond French regional newspaper "La Provence".

"In line with our expressions of interest in the media sector and recently in M6, we confirm that we have crossed the threshold of 5% of the (share) capital of M6," a spokesperson for CMA CGM said, adding that the transaction was made "in agreement" with M6's main shareholder, Bertelsmann's RTL Group.

CMA CGM's spokesperson said the shipping group supported M6's strategy and didn't intend to take control of the TV station.

RTL, which owns 48% of M6, scrapped a plan to sell its controlling stake in M6 in October, meaning that its parent company Bertelsmann will have to wait five years before considering any new bids for the company.

Saade was part of a consortium of high-profile French entrepreneurs that expressed interest in buying RTL's stake in M6 at the time, a source close to the matter has said.

(Reporting by Gus Trompiz and Mathieu Rosemain; Editing by Susan Fenton)