SAN SALVADOR, June 9 (Reuters) - El Salvador’s congress at midnight on Tuesday approved a proposal from President Nayib Bukele for a law to classify bitcoin as legal tender, making the Central American nation the first in the world to do so. A majority of lawmakers voted in favor of the initiative to create a law that will formally embrace the cryptocurrency, despite concern about the potential impact on El Salvador’s program with the International Monetary Fund. (Reporting by Nelson Renteria, Writing by Daina Beth Solomon, editing by Louise Heavens) Our Standards: The Thomson Reuters Trust Principles.