Police are investigating two fights at the National University of Samoa (NUS) that have led to more than five students being detained, while the university has launched a separate disciplinary process involving 18 identified students.

The fights occurred on Friday last week and Tuesday, with videos of both incidents widely shared on social media.

Police officers attended the NUS campus on Thursday morning and detained more than five students believed to have been involved in the altercations.

Acting Police Commissioner Leiataualesa Samuelu Afamasaga confirmed police are investigating the incidents but declined to comment further while inquiries continue.

"We are investigating the matter," he said.