United Airlines has been caught up in a Twitter row after two girls were reportedly barred from flying for wearing leggings.
The incident happened on a flight from Denver to Minneapolis on Sunday morning, activist Shannon Watts said.
The airline said the girls were travelling on a special pass, for employees and their guests, which has a dress code.
United then issued a clarification via Twitter, saying that regular passengers were welcome to wear leggings.
Watts tweeted about what happened to five girls when they tried to board a flight at Denver airport, the BBC reported.
She said a United gate agent was “forcing” the girls, one of them aged 10, to change their clothes or wear dresses over the leggings.
She said three of the girls were allowed to fly after putting dresses over the top of their clothing, but two were prevented from boarding.
United said: “One of the benefits of working for an airline is that our employees are able to travel the world. Even better, they can extend this privilege to a select number of what we call ‘pass riders.’
“These are relatives or friends who also receive the benefit of free or heavily discounted air travel – on our airline as well as on airlines around the world where we have mutual agreements in place for employees and pass riders.
“When taking advantage of this benefit, all employees and pass riders are considered representatives of United. And like most companies, we have a dress code that we ask employees and pass riders to follow.
“The passengers this morning were United pass riders and not in compliance with our dress code for company benefit travel.
“We regularly remind our employees that when they place a family member or friend on a flight for free as a standby passenger, they need to follow our dress code.”