Security officers detain a protester at the University of Southern California on Friday. AFP

The action was taken after protesters |crossed the line," the school said in a statement on social media platform X.

The protests against Israel's war with Hamas began at Columbia University earlier this month before spreading to campuses across the country.

They have posed a major challenge to university administrators who are trying to balance campus commitments to free expression with complaints that the rallies have crossed a line.

Police have carried out large-scale arrests at universities in recent days, at times using chemical irritants and tasers to disperse demonstrators.

In its statement, Northeastern said campus police backed by local law enforcement moved in Saturday to clear "an unauthorized encampment" on the campus.

"What began as a student demonstration two days ago was infiltrated by professional organisers with no affiliation to Northeastern," the school said.

It added that detained individuals who produced a valid school ID have been released and will face disciplinary proceedings, not legal action.

"Those who refused to disclose their affiliation were arrested," the school said.

Agence France-Presse