NEW YORK (Reuters) - Billionaire Len Blavatnik's Access Industries has won the auction to take control of Warner Music Group Corp with an offer of $8.25 a share, the company said on Friday.

The agreement values the world's third largest music company's combined equity and debt at around $3.3 billion. The all-cash deal is expected to close in the third quarter.

Warner Music, whose artists include Bruno Mars, Green Day and Led Zeppelin, will become an autonomous unit of Access, alongside industrials assets in natural resources and chemicals as well as media and telecommunications.

Blavatnik beat out last-round bids from Tom and Alec Gores' Platinum Equity/The Gores Group and Sony Corp in partnership with Guggenheim Partners and investor Ron Perelman.

Blavatnik is a long-time associate of Warner Music Chief Executive Edgar Bronfman Jr and his father. He was a director of Warner Music from 2004, when Bronfman led a buyout of the company from Time Warner Inc up until 2008. Before the this latest buyout deal Blavatnik already owned around 2 percent of Warner Music.

Bronfman and private equity firms Thomas H Lee and Bain Capital Partners together hold around 56 percent of the company's outstanding shares and have entered into a voting agreement with Access to vote in favor of the merger.

Access secured deal financing from Credit Suisse and UBS, who were also advisors on the deal. Warner Music was advised by Goldman Sachs and AGM Partners.

(Reporting by Yinka Adegoke, editing by Gerald E. McCormick)