WASHINGTON, Nov 13 (Reuters) - The U.S. Federal Trade Commission filed a lawsuit aimed at stopping Methodist Le Bonheur Healthcare, which has four hospitals in the Memphis area, from acquiring two more in a deal valued at $350 million, the agency said on Friday.

The five FTC commissioners voted unanimously to bring the lawsuit, which would stop Methodist from buying two hospitals, known as St. Francis, now owned by Tenet Healthcare Corp.

The purchase would reduce the number of hospital systems providing general acute care in the Memphis area from four to three and give Methodist some 60% of that market, the agency said.

The companies said in a statement that they were "surprised" by the FTC opposition. "We are reviewing this recent action by the FTC and actively considering next steps," said Sally Hurt-Deitch, CEO of Saint Francis Healthcare and Michael Ugwueke, president of Methodist Le Bonheur, in a joint email statement.

(Reporting by Diane Bartz Editing by Nick Zieminski)