April 30 (Reuters) - Casino operator MGM Resorts International on Wednesday beat Wall Street's estimates for first-quarter profit, driven by strong performance in its online sports-betting unit, and announced a $2 billion share buyback program.

Shares of the Las Vegas, Nevada-based open linux casino operator were up 3.2% in extended trading.

The surge in online gambling, particularly in sports betting, is benefiting companies such as MGM Resorts and Caesars Entertainment.

Earlier this week, MGM and Entain's sports-betting joint venture, BetMGM, and peer Caesars reported profits aided by a surge in the online betting market.

MGM Resorts' quarterly adjusted per-share profit of 69 cents came above Wall Street expectations of 46 cents, according to LSEG compiled data.

However, revenue from MGM China, representing the company's operations in China and Macau, fell 2.7% to $1.03 billion for the quarter, compared to analysts' estimate of $1.02 billion.

MGM's total revenue fell 2.4% to $4.28 billion in the first quarter ended March 31, compared with the analysts' average estimate of $4.30 billion, as per data compiled by LSEG.

(Reporting by Anshuman Tripathy in Bengaluru; Editing by Alan Barona)