A leading California university has cancelled its graduation ceremony as protests over Gaza continue to spread on college campuses across the US.

The University of Southern California (USC) in Los Angeles cited "new safety measures" in disbanding the event.

Hundreds of people have been arrested on dozens of campuses where protests and encampments have sprung up in support of Palestinians in Gaza.

Universities have brought in police to force students to leave.

But some are also negotiating. At Columbia University in New York City, where the protests began last week, a Thursday night deadline for an end to the encampment was dropped.

Talks were showing progress and would continue, the university said.

At Atlanta's Emory University, 28 demonstrators were arrested on Thursday after refusing to leave.

Emory's police force said protesters had "pushed past" officers protecting the area set up for commencement on Thursday morning.