Rotorua's mayor has expressed concern over recent attacks, and says at least one incident could have been gang-related.

A 15-year-old girl was assaulted by three other girls outside Rotorua Library in the CBD on Monday afternoon.

This follows a 13-year-old girl being beaten and left bloodied in an unprovoked attack last week.

Mayor Tania Tapsell says she's working alongside the police to devise solutions and prevent similar acts of violence.

"Regardless of this, we should not be having to worry about community safety in our public spaces."

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