UPDATE 2-Wynn sets $500 mln buyback; shares up 15 pct

(Adds details of second-quarter forecast)

LOS ANGELES, July 10 (Reuters) - Casino operator Wynn Resorts Ltd (WYNN.O) said on Thursday it would increase its share buyback program by $500 million, and its stock jumped nearly 15 percent in extended trade.

In a statement, Wynn said the new buyback program would come on top of a previously announced $1.2 billion repurchase plan.

Separately, Wynn said second-quarter operating income for its Las Vegas casino, on a GAAP basis, would be between $18 million and $22 million. That is down from $63.4 million in the same period last year.

Wynn's Las Vegas casino has drawn fewer consumers to the resort as current U.S. economic woes such as the declining home market and higher gas prices have forced Americans to cut discretionary expenses.

The casino expects its average daily room rate will drop to $302 during the second fiscal quarter from $311 in the same quarter a year ago.

A dip in table game winnings may negatively affect Wynn's second-quarter results. The Las Vegas casino won only 20.4 percent of money gambled at table games -- just below the casino's typical range of 21 to 24 percent and down from 24.2 percent during the same quarter in 2007.

Unlike its American sister resort, the Wynn Macau casino is expected to continue its booming growth. Operating income could double, or nearly double, to between $100 million and $106 million from $53.2 million last year.

Wynn shares rose to $80.15 in extended trade after closing at $69.94 on Nasdaq, down 10 percent. (Reporting by Nichola Groom and Jennifer Martinez; editing by Jeffrey Benkoe, Gary Hill)