The sign outside the Sam's Club is seen in Bentonville, Arkansas June 5, 2014. REUTERS/Rick Wilking

(Reuters) - Sam's Club, a unit of Wal-Mart Stores Inc WMT.N, said it had closed a series of stores following a review, the membership-only store chain said in a tweet on Thursday.

Business Insider, citing Wal-Mart, reported that Sam's Club was closing 63 stores and laying off thousands of workers. (read.bi/2qYH8bE)

Sam'S Club's tweet comes after local news outlets in Arizona, Alaska, Texas, New Jersey, Indiana and New York reported that some Sam's Club stores closed abruptly on Thursday, with employees learning of the move as they arrived for work. (bit.ly/2DjkkWv)

“Closing clubs is never easy and we’re committed to working with impacted members and associates through this transition,” Sam’s Club said on Twitter.

Sam’s Club was not immediately available for comment.

Earlier in the day, Wal-Mart said it would raise entry-level wages for U.S. hourly employees to $11 an hour in February as it benefits from last month’s major overhaul of the U.S. tax code.

Sam’s Club said pharmacies at the closed locations would stay open for at least two weeks and the company would work with the respective state’s Board of Pharmacy to help customers with the transition.

Wal-Mart's shares were up 0.5 percent in afternoon trading, while shares of Costco Wholesale Corp COST.O, which competes with Sam's Club, were up 2.7 percent.