Police in Portland, in the US State of Oregon, say four people were arrested during demonstrations near City Hall.

The dueling protests involved antifacists known as antifa and right-wing groups.

Some reports showed demonstrators punching and assaulting members of the opposing side on Sunday afternoon.

A Portland police spokesman says some people were treated for injuries but no one needed to be taken to the hospital.

The Oregonian/Oregon Live reported the dueling protests got underway on Sunday peacefully at first. Then there was shoving, a small bonfire was lit and punches were thrown.

Police used pepper spray to quell the crowds as Patriot Prayer supporters started marching.

Two of those arrested were facing disorderly conduct charges. One other was charged with failure to comply with an order.

Charges against the fourth person were not immediately known.