Festival organisers are yet to comment.
A 19-year-old woman has alleged she was sexually assaulted by an unknown male in the mosh pit at Falls Festival in Marion Bay on Friday.
As ABC reports, Tasmanian police are now investigating the claim believed to have happened at around 9.30pm during The Jungle Giants' set.
"The key message here is that although the mosh pit itself is designed for close contact, any form of touching without the other person's consent is not OK," Detective Constable McVilly said in a statement.
"We want patrons to feel safe and enjoy the event so we urge anyone witnessing this kind behaviour to report it immediately."
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The allegation comes after five female punters reported incidents of sexual assault at last year's Marion Bay shows.
The Music has contacted Falls Festival for comment.