British supermarket giant Tesco Plc announced Wednesday that Tim Mason, chief executive of the American segment of its company, Fresh & Easy Marketplace Inc., has resigned. Tesco also announced that it may close or sell some or all of its Fresh & Easy stores, which are headquartered in El Segundo. The company said it will not announce any decisions until April. The grocery chain has faced continued financial struggles in recent months and received an ultimatum from its English parent company in October, restricting capital with a demand to make the stores more profitable. Now, the company has hired Greenhill & Co. Inc., a New York financial advisory firm, to review options for the beleaguered stores. “It is now clear that Fresh & Easy will not deliver acceptable shareholder returns on an appropriate timeframe in its current form,” Tesco said in a statement. “In recent months, we have had a number of approaches from parties interested in acquiring either all or part of Fresh & Easy, or in partnering with us to develop the Fresh & Easy business.” Fresh & Easy has nearly 200 stores throughout California, Arizona and Nevada. It has 34 stores in L.A. County, including about 13 in the greater Valley region. A Fresh & Easy Express store opened in Encino Oct. 24. Shares for Tesco closed up 10.26 pounds ($16.51), or more than 3 percent, to 336.91 pounds ($542.19) Wednesday on the London Stock Exchange.