Uproar as United grounds girls wearing leggings

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The airline says the passengers didn't meet their "high" standards (Getty)

United Airlines has faced an online backlash after barring two girls from a US domestic flight for wearing leggings in an apparent breach of their clothing policy.

The fashion feud was live-tweeted by gun control group Moms Demand Action founder Shannon Watts.

It's even had some celebrities get on board, including Patricia Arquette and Chrissy Teigen.

Ms Watts first documented the gate lounge drama on Sunday (local time) on a flight from Denver to Minneapolis.

"A United gate agent isn't letting girls on leggings get on flight from Denver to Minneapolis because spandex is not allowed?

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The airline says casual dress for passengers with tickets, rather than those stand-by, is fine (Getty)

"She's forcing them to change or put dresses on over leggings or they can't board. Since when does United police women's clothing?" Ms Watts wrote.

While some were forced to change before they could board, two others weren't allowed on the flight at all, Ms Watts claimed. One of those involved was a 10-year-old girl.

In response, United pointed to its dress code as the reason why the passengers weren't allowed to board or had to change.

"Casual attire is allowed as long as it looks neat and is in good taste for the local environment.

"The attire of the pass traveller [stand-by passenger] did not meet our rules," United response actress Arquette, who'd sought to clarify the policy, read.

Because those affected were eligible dependents of United employees, the airline said it held them to the "highest of standards" as they were United representatives.

It said casual wear for ticketed passengers "is fine".

That didn't stop the criticism coming thick and fast from Twitter users accusing the policy of being sexist. Celebrity Teigen who said she'd flown on United before with "literally no pants on. Just a top as a dress".

"Next time I will wear only jeans and a scarf."

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