SAN SALVADOR (Reuters) - The U.S. dollar will continue to be legal tender in El Salvador with bitcoin transactions by choice only, the nation’s top trade official said on Monday, after President Nayib Bukele faced criticism for aiming to adopt bitcoin as legal tender. Trade and Investment Minister Miguel Kattan also said bitcoin operations would be linked to the dollar exchange rate in the Central American country. Reporting by Nelson Renteria; Writing by Daina Beth Solomon; Editing by Leslie Adler Our Standards: The Thomson Reuters Trust Principles.