DENVER (AP) — United Airlines says regular-paying flyers are welcome to wear leggings aboard its flights, even though two teenage girls were barred by a gate agent from boarding a flight from Denver to Minneapolis on Sunday because of their attire.

An airline spokesman said that the girls were traveling under an employee travel pass that includes a dress code.

The move sparked a wave of online criticism against United.

Activist Shannon Watts of Denver tweeted that she witnessed Sunday’s events and questioned United’s decision to police women’s clothing.

Watts said the girl’s father was allowed to board while wearing shorts and called the airline’s policy sexist.

Comedian Sarah Silverman tweeted that she would change her United flight bookings to other airlines for a tour next month because of the leggings issue.

Regularly ticketed passengers are not subject to the same dress code and can wear leggings, United spokesman Jonathan Guerin said. But the airline was standing by its policy for pass travelers because they are essentially representing the company, he said.

“We would ask the same of pass riders who were wearing flip-flops or who were wearing clothing that revealed their undergarments or torn, tattered jeans,” Guerin said.

The longstanding policy requires those who enjoy the perks of airline employment, which include free travel passes for family and guests, to present themselves in a way that represents the airline well.

According to the policy, which was provided to CNNMoney by a United employee, “pass riders” aren’t allowed to wear clothing that doesn’t look “neat and professional.”

That includes form-fitting lycra or spandex tops, pants and dresses, offensive or derogatory words or graphics on clothing, “excessively dirty” clothing that has holes or tears, or anything that is “inappropriately revealing.”

“Pass riders should use good judgment and common sense” about items not explicitly on their list, according to the policy.

And it says dress attire for those using the perks “should always meet or exceed the casual standards” of the flying public.

Screenshot of United Airline’s statement after dress code criticism (Credit: United Airlines)

Chicago-based United sought to clarify its stance in a post on its website late Sunday titled, “To our customers … your leggings are welcome!”

The post said employees are “regularly reminded” about its dress code.

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