NEW YORK, April 23 (Reuters) - Wal-Mart Stores Inc's (WMT.N: Quote, Profile, Research) Sam's Club warehouse division said on Wednesday it is limiting sales of several types of rice, the latest sign that fears of a rice shortage are rippling around the world. Sam's Club, the No. 2 U.S. warehouse club operator, is limiting sales of the 20-pound (9 kg), bulk bags of rice to four bags per customer per visit, and is working with suppliers to ensure the products remain in stock.