Sept. 14 (Bloomberg) -- Blackstone Group LP notified European Union regulators of its plan to buy Hilton Hotels Corp., the second-biggest U.S. hotel chain, setting off an antitrust review of the $20 billion deal.

The Hilton purchase is a record for the hotel industry. Blackstone, which already owns the La Quinta lodging chain, joins Apollo Management LP and Texas Pacific Group in targeting hotel companies for their cash flow and real estate. Worldwide, hotel acquisitions more than doubled in the first half of this year, to $81.4 billion.

The European Commission, the antitrust arm of the EU's 27 nations, said on its Web site that the notification was made today. The Brussels-based regulator, which can block the deal or force changes such as asset sales, will rule on the transaction by Oct. 19.

Including the assumption of debt, the transaction totals $26 billion. Hilton, second in size to Marriott International Inc., has more than 2,800 locations. The Hilton chain has more than 480,000 hotel rooms worldwide under brands including Waldorf- Astoria and Doubletree.

The Hilton purchase eclipses the 1998 takeover of ITT Corp. by Starwood Hotels & Resorts Trust for $14.6 billion, including debt.

To contact the reporter on this story: Matthew Newman in Brussels at Mnewman6@bloomberg.net.