Muhammad Ali Jr. was detained for 2 hours at the Fort Lauderdale-Hollywood International Airport ... and he's ready to sue because he thinks it's because he's Muslim.
Ali Jr.'s spokesman, Chris Mancini, tells TMZ ... his client was returning from Jamaica with his mother, Khalilah Ali -- Ali's first wife -- on February 7 when immigration officers stopped them. She got through, but he was taken to a small room for 2 hours and questioned.
Mancini says Ali's 44-year-old son was asked twice if he's Muslim, and also where he got his name.