BERLIN, March 12 (Reuters) - European broadcaster RTL confirmed on Friday it was exploring the sale of its controlling stake in French broadcaster Groupe M6, as it reported a 26% slide in annual core profit due to the coronavirus pandemic.

Chief Executive Thomas Rabe said he saw a strong case for consolidation in the European media industry - in particular for in-country TV merger deals - as U.S. streaming giants increasingly capture the attention of viewers.

"It's part of our strategy to be pro-active on consolidation, and to actually do something," Rabe told reporters on a conference call.

Rabe, who also heads RTL's controlling shareholder Bertelsmann, approached potential bidders in January to explore a sale of M6 as he undertakes a broader restructuring of the German publishing group.

He reiterated what RTL said at the time that the company was reviewing its options for its M6 stake. He declined to be drawn on reported interest in the stake, nor would he give a timeline on when a deal might be negotiated.

Conglomerates Vivendi and Bouygues are bidding for Bertelsmann's 48% stake in M6, two sources close to the matter said on Thursday. The stake has a market value of 1.1 billion euros ($1.3 billion).

French telecoms tycoon Xavier Niel and Czech billionaire Daniel Kretinsky are interested in Bertelsmann's M6 stake, added the sources, who requested anonymity because the talks are private.

Italy's biggest commercial broadcaster, Mediaset, is also looking into the asset, a separate source said.

RTL's group revenue fell by 9.5% in 2020 to 6 billion euros, while core profit declined 26% to 853 million euros. The company forecast that revenue would grow organically by 8% this year and for core profit to reach 975 million euros.

Management will propose a dividend of 3 euros per share, after cancelling the payout last year. ($1 = 0.8369 euros) (Reporting by Douglas Busvine; Editing by Riham Alkousaa, Maria Sheahan and Jane Merriman)