Mumford and Sons opt-out from Sweden's biggest festival

Mumford and Sons say they will boycott a Swedish music festival after reports emerged that 17 women were sexually assaulted at the event last weekend.

Authorities received five reports of rape and 12 of sexual assault during Bravalla, Sweden's biggest festival.

"We're appalled to hear what happened," wrote Mumford and Sons on Facebook.

"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."

They added: "We won't play at this festival again until we've had assurances from the police and organisers that they're doing something to combat what appears to be a disgustingly high rate of reported sexual violence."

Swedish pop star Zara Larsson also wrote a series of furious tweets after hearing a woman had been raped while she played the festival.

"You deserve to burn in hell," she wrote. "[Damn] you for making girls feel insecure when they go to a festival. I hate guys. Hate hate hate.

"How am I supposed to take it seriously when you say 'not all men', 'I'm a nice guy, I don't rape'? Where do all the 'nice guys' go when girls are raped? Are you too busy telling women how nice you are?"