Police are investigating serious allegations of “inappropriate sexual behaviour” of more than a dozen high school students.

Police say the incidents happened at a multi-school social event on Saturday, July 31.

The victims from a number of different schools claim they were groped and indecently assaulted.

A WA Police Force spokesperson said investigations into the matter are ongoing.

“Police are working closely with the affected schools to resolve this matter and to ensure that all appropriate welfare and support measures are in place.”