Portland on high alert as duelling far-right and extremist groups prepare to protest

The city of Portland is braced for violence with anti-fascist groups expected to face down a right-wing rally that’s expected to draw demonstrators from across America.

Self-described anti-fascists — known as Antifa — say they will confront the rally in Oregon while leaders from the far-right urged their followers to turn out in large numbers to protest the arrests of six members of right-wing groups in the run-up to the event.

Authorities have asked residents not to call 911 unless it's a life-threatening emergency and to stay away from the heart of the downtown area.

Some city streets will be closed Saturday, as well as a major bridge connecting the east and west sides of the city.

Donald Trump escalated the tensions on Saturday morning but tweeting that the city is being “watched very closely” and that federal authorities are considering designating Antifa a terrorist organisation.

Patriot Prayer's Joey Gibson, who is not involved in this weekend's rally but organised similar events in 2017 and 2018 that have become violent, surrendered on Friday to an arrest warrant for felony rioting. He was present at a confrontation that broke out on May 1 outside a bar where Antifa members had gathered after a May Day demonstration.

During a livestream on Facebook, Gibson accused the police of playing politics by arresting him but not the masked demonstrators who beat up conservative blogger Andy Ngo at a June 29 rally.

A video of the attack went viral and led the Proud Boys to organise Saturday's event.

Gibson used the alleged double-standard by police to urge a higher turnout at Saturday’s event: “What I'm saying to everybody who's listening to this (is) they're trying to shut you guys up. They want you to not show up in Portland, they want to put fear in your hearts," Gibson said.

"When a government pushes back like that, we don't bend the knee.”

Portland Police Bureau spokeswoman Tina Jones said officers were focused solely on maintaining order, and not about favouring left-wing counter-protesters.

"We receive criticism no matter what. It's either too much, not enough, you arrested this group and not this group," Jones said. "It seems like some people are keeping score, and that's not what it's about on the law enforcement side. One hundred percent, it's about public safety."

In addition to the Proud Boys, the white nationalist American Guard and the Three Percenters, a far-right militia, have said they will have members in Portland. Hate group watchdogs say the Daily Stormers, a neo-Nazi group, are also expected.

The Oath Keepers, another far-right militia group, said in a statement they were pulling out of the rally because organisers have not done enough to keep white supremacist groups away.

Agencies contributed to this report