Mumford & Sons is taking a strong stand against sexual assault after learning there were 17 reports of sexual assault at a music festival the band headlined over the weekend.

In a Facebook post published on Tuesday, Mumford & Sons said it refuses to perform at Sweden's Bravalla music festival again until authorities can effectively tackle the problem of sexual assaults at shows:

"We're appalled to hear what happened at the Bravalla Festival last weekend," the members wrote. "Festivals are a celebration of music and people, a place to let go and feel safe doing so. We're gutted by these hideous reports. We won't play at this festival again until we've had assurances from the police and organizers that they're doing something to combat what appears to be a disgustingly high rate of reported sexual violence."

During the same weekend, 35 sexual assaults were reported at Putte i Parken, another Swedish music festival; the youngest reported victim was 12 years old, according to BBC. A victim's unidentified friend also alleged that security officials did not seem to take sexual assault reports seriously.

"A guy ran his hand between the legs of one of my friends," the unnamed victim's friend told Swedish publication AftonBladet, as reported in English by BBC. "When she went to a bouncer, she was asked if she was drunk. I don't know what the bouncers are doing there if they can't help when people do this."

Swedish singer Zara Larsson, also a headliner for this year's Bravalla, condemned the reported sexual assaults on Twitter:

"F--k you who shamelessly raped a girl in the audience," she wrote, as translated by Fuse TV. "You deserve to burn in hell.”

Sexual assaults at concerts are a major issue.

Late last year, several European teenagers formed the group Girls Against to draw attention to the problem of sexual assaults at concerts. Five girls formed the group after one of the members, Hannah Camilleri, was assaulted during a Peace concert in Glasgow, Scotland.

After Camilleri tweeted about the assault, Peace member Harry Koisser showed support for Girls Against on social media:

The alarming reports of sexual assault at music festivals are not new. In 1999, four women reported they were raped at the Woodstock music festival in New York. Crisis counselor David Schneider told The New York Times at the time that he witnessed a bunch of men sexually assaulting multiple women during a Korn performance.

"It seemed inconceivable that somebody would be raping somebody right in front of thousands of people,'' he said. ''But then I saw the hands holding them down and the girls were flailing.''