LOS ANGELES, Apr. 28 (Reuters) - Protests at U.S. universities showed no sign of slowing over the weekend, with more arrests on campuses across the country and skirmishes between pro-Israeli and pro-Palestinian demonstrators at UCLA, where a tent encampment was set up last week.

As the size of the pro-Palestinian encampment at the University of California at Los Angeles expanded in recent days, counter-protesters have become increasingly vocal and visible on the campus, although both sides remained peaceful until Sunday.

That changed when some demonstrators broke through a barrier that the school had set up to separate the two factions, Mary Osako, UCLA's vice chancellor for UCLA strategic communications, said.

Members of both factions shoved one another and shouted slogans and insults, and in some cases traded punches. Pushing and shoving persisted for some time among pockets of demonstrators, but campus police armed with batons eventually separated the sparring groups.

"UCLA has a long history of being a place of peaceful protest, and we are heartbroken about the violence that broke out," Osako said in a statement.

Chanting had ceased by around 3:30 p.m. local time and pro-Palestinian protesters trickled back to the encampment, according to the Reuters photographer at the scene.

Los Angeles police were not involved in quelling the disturbance, a representative of the campus police said, and no arrests had been made.

The dueling demonstrations on the UCLA campus involved at least some people from outside the university, according to an earlier statement by the university, which said it had allowed two groups on campus to express their views.

Members of the Harriet Tubman Center for Social Justice planned to support the right of students to protest, according to the statement, while Stand in Support of Jewish Students, in partnership with Israeli-American Council, planned to oppose hatred and antisemitism on campus.

Photo from Reuters