(Reuters) - Storm Isaac strengthened into a Category 1 hurricane on Tuesday as it approached the northern Gulf coast, the U.S. National Hurricane Center said in its latest bulletin.

"Reports from an Air Force Reserve hurricane hunter aircraft indicate that maximum winds associated with Isaac have increased to 75 miles per hour (120 kms per hour)," the NHC said.

(Reporting by Soma Das in Bangalore; Editing by Lisa Von Ahn)