Muhammad Ali Jr, the son and namesake of the late boxing great, was questioned about his identity at a Washington DC airport before boarding a flight on Friday, one day after he testified before lawmakers about a similar incident at another airport, a US Congresswoman said.

"To me it's an act of retaliation, in addition to him continuing to be religiously profiled," said Representative Debbie Wasserman Schultz, a Democrat from Florida, who was on the same flight as Ali.

Muhammad Ali Jr previously said he was detained at an airport in Florida on February 7 after arriving on a flight from Jamaica and that federal agents asked about his Muslim religion.

Ali testified about the incident on Thursday before Democratic members of the House Judiciary Committee. Ms Wasserman Schultz said she does not believe it was a coincidence that Ali had trouble boarding a flight from Washington.