An absurd dress code requirement set by United Airlines ignited a stir on Twitter on Sunday. The rule was found by Shannon Watts, the founder of the anti-gun violence group Moms Demand Action when she tweeted about seeing a gate agent refused to allow "girls in leggings" board a flight from Denver to Minneapolis "because spandex is not allowed."

"I guess @united not letting women wear athletic wear?" Watts tweeted to her more than 32,000 followers.

United's initial response said that it "shall have the right to refuse passengers who are not properly clothed", however, backfired and caused confusion as well as anger online.

Many were concerned and asked whether the airline was referring that it will not allow paying customers to board just because they wore yoga pants.

"Leggings are the business attire for 10-year-olds. Their business is being children," tweeted actress Patricia Arquette, as reported by CNN.

The airline tweeted that the passengers who were flying were not in compliance with its dress code policy, hours later.

Apparently, the airline company policy requires those who enjoy the perks of airline employment that offer free travel passes for family and guests, to present themselves in a proper manner.

So family and guest of employees are not allowed to wear clothing that is not neat and professional if they are flying using the free travel passes.

According to the airline, improper clothing includes form-fitting lycra or spandex tops, pants and dresses, offensive words or graphics on clothing, not hygienic 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 and should always meet or exceed the casual standards" of the flying public, the airline added.