SINGAPORE, Aug 18 (Reuters) - Gail (India) (GAIL.NS) has issued a tender seeking to buy a liquefied natural gas (LNG) cargo for delivery into India and offering a cargo for loading from the United States, two industry sources said on Wednesday. It is seeking the cargo for September delivery into Dahej, India and has offered a cargo for loading from the Cove Point plant in the United States during March 4-6, one of the sources said. The tender closes on Aug. 19, the source added. The Indian importer has 20-year deals to buy 5.8 million tonnes a year of U.S. LNG, split between Dominion Energy"s (D.N) Cove Point plant and Cheniere Energy"s (LNG.A) Sabine Pass site in Louisiana. Reporting by Jessica Jaganathan; Editing by Jacqueline Wong Our Standards: The Thomson Reuters Trust Principles.