A mother-of-two says she was forced to urinate in a cup while seated on a United Airlines flight after air cabin crew staff refused to let her use the toilet.

Nicole Harper, who works as a nurse, says she was humiliated as she was left to squat and urinate in front of family and other passengers during the flight from Houston to her home in Kansas City on 10 April.

The incident came just a day after another passenger, 69-year-old David Dao, was injured while being forced off another United flight that was overbooked. Video footage of the incident later emerged online, causing a public relations nightmare for the company.

On her own flight, Harper claimed the flight attendant would not allow her to visit the toilet because the seatbelt sign was illuminated.

"After explaining that I have an overactive bladder and would either need to use the restroom or pee in a cup, I was handed a cup by flight attendants," Harper said in a Facebook post about the incident.

She added: "You would think peeing in a cup on an airplane in front my family and strangers, would be the worst part of this story. But the way I was treated by the flight attendants afterwards was worse."

Harper said after filling two cups with urine as her husband sat next to her, she was then "shamed" into walking down the aisle to empty them in the toilet.

She wrote on Facebook: "I was handed a cup by flight attendants. Bad enough? No, crew then escorted me to the restroom (now it's safe to get out of my seat), shaming me down the aisle while other passengers overlooked.

"The flight attendants treated me like I had committed a crime, stating they would be filing a report, calling in the hazmat team to clean the entire row (let me mention there was no mess involved) and told me I would need to talk with the pilot after the flight!

"I guess they would have preferred me to pee in the seat? After all they were the ones that gave me the cups knowing what I was planning to do with it."

Harper submitted a complaint to the airline but had not heard back from their customer service team, so penned the Facebook post.

United Airlines has now released a statement about the incident. The airline said: "Customer safety is always our first priority. Initial reports from the Mesa Airlines flight attendants indicate that Ms Harper attempted to visit the lavatory on final descent and was instructed to remain seated with the seat belt fastened per FAA regulations.

"The situation as described by Ms Harper and our employees is upsetting for all involved.

"We have reached out to Ms Harper and our flying partner Mesa Airlines to better understand what occurred."

Harper's flight was the day after 69-year-old David Dao was injured while being forced off a United flight that was overbooked.

It also comes amid a string of incidents where passengers have publicly complained about the frustrations of flying.

nicole harper
Nicole Harper says she felt 'shamed' during the incident KPTV