Protesters in Portland have knocked down statues of two former US presidents in a show of “rage” against a federal holiday that celebrates Christopher Columbus’ arrival.

Within 10 minutes, monuments of Theodore Roosevelt and Abraham Lincoln were toppled by protesters who gathered for an event dubbed the “Indigenous Peoples Day of Rage”.

The group threw chains around Mr Roosevelt’s statue and splashed red paint on the base before pulling down the figure.

They then used a blowtorch on the base of the statue.

About eight minutes later, they overturned Mr Lincoln’s statue and spray-painted ‘Dakota 38’ on the base, referring to 38 men from Dakota who were ordered by Mr Lincoln to be hanged after fighting white settlers in the Dakota War of 1862.

The protesters were protesting about Columbus Day, which is celebrated on on October 12 and has been a federal holiday in the US for more than 80 years.

Columbus was an Italian explorer and a polarising figure said by Native American advocates to have spurred centuries of genocide against indigenous populations in the Americas.

Police declared the situation a riot but did not intervene for some hours. Photo: AAP

Historians have said Mr Roosevelt expressed hostility toward Native Americans, once saying: “I don’t go so far as to think that the only good Indians are dead Indians, but I believe nine out of every 10 are.”

Local news outlet The Oregonian reported that protesters moved on to the Oregon Historical Society, unfurling a banner that read, “Stop honouring racist coloniser murderers.”

A mural on the attached Sovereign Hotel building depicting the historic Lewis and Clark exploration expedition was splattered with red paint, The Oregonian said.

After toppling the statues, the crowd began smashing windows at the hHistorical society and then went on to the Portland State University Campus Public Safety office.

Police later declared the event a riot and ordered the group to disperse.

Police said anyone involved in “criminal behaviour, including vandalism” was subject to arrest.

It’s unclear if any arrests were made.

The monuments are the latest statues to come down in a wave of removed monuments and protests sparked by the May 25 death of George Floyd in Minneapolis police custody.

-with AAP