The alleged incident took place just two days after Farah won his second Rio gold in the 5,000m. His family were boarding a 9.53am flight from Atlanta, Georgia, to their home in Portland, Oregon, in the US on August 22.
The 33-year-old was still sporting a Team GB holdall and Rihanna was hugging a Pride the lion Team GB cuddly mascot. Witness Jen Erdmann, a US government worker, said the commotion began as soon as the Farahs attempted to board.
With no separate queue for first-class passengers, the group were told to wait until the flight had boarded, it is said
Mrs Erdmann said: 'The agent told her to stand to the side and wait. When she was right next to the gate agent she started laying into her. I didn't even recognise Mo but was listening because of this argument.
'It wasn't at the top of her voice but loud. Mo stood there with their daughter but if that were my kids they would be so embarrassed. She called the agent disrespectful a lot of times.
'When a supervisor arrived Tania referred to the agent as "this pathetic little woman",' said Mrs Erdmann, from Atlanta. 'She said she was taking her sad little life out on them.
She was swearing a lot, it was peppered throughout. She talked about "f****** problems on this f****** airline".
'She kept saying the woman was being disrespectful and I thought she meant it in terms of being a celebrity.'