The city, the biggest in the US state of Oregon, has seen nightly protests for nearly two months, initially sparked by the death in Minneapolis of unarmed African American George Floyd.

Protesters are surrounded by tear gas near the Mark O. Hatfield federal courthouse in downtown Portland, Oregon late on July 24, 2020.
Protesters are surrounded by tear gas near the Mark O. Hatfield federal courthouse in downtown Portland, Oregon late on July 24, 2020. (AFP)

Police and federal agents fired tear gas and forcefully dispersed protesters in the US city of Portland early on Saturday during the latest demonstrations against racism and police brutality.

The city, the biggest in the state of Oregon, has seen nightly protests for nearly two months, initially sparked by the death in Minneapolis of unarmed African American George Floyd.

It is also now the scene of a highly controversial crackdown by federal agents ordered by US President Donald Trump — one that is not supported by local officials, and which many said smacked of authoritarianism.

READ MORE: Arrest of racial inequality protesters in Portland sparks outrage 

Friday's demonstration was mainly peaceful, with crowds playing music and dancing, blowing soap bubbles and setting off fireworks.

But it ended —  like many before it — in a showdown between protesters and police, which escalated in a haze of tear gas and flash-bang devices.

One group of protesters formed a line with umbrellas and makeshift shields to try to protect themselves, as at least two fires burned outside the fences around a federal courthouse.

'Little green men'

Tear gas was first fired around 11:00 pm. By 2:30 am police and federal agents were clearing the scene outside the courthouse with tear gas, pushing protesters back.

Earlier, protesters who spoke to AFP complained of the federal agents' presence in the city and voiced their support for the Black Lives Matter movement, which helped drive demonstrations across the country for weeks after Floyd's killing.

"I don't like what's happening down here, what Trump is doing," Mike Shikany, a 55-year-old aerospace engineer, said, adding he did not "want to get anywhere near the little green men," meaning the federal troops.

Portland retiree Jean Mullen, 74, said that without pressure nothing would change.

"It's time to become the country we always brag about being. And we can't brag anymore, about anything. We aren't first in anything and it's a terrible, terrible thing to see at the end of my life," she said.

The inspector general of the US Justice Department on Thursday opened an official investigation into the federal crackdown, but a federal judge in Oregon on Friday rejected a legal bid by the state to stop agents from detaining protesters.

READ MORE: US charges arrested Portland protesters 

The city's Democratic mayor Ted Wheeler has accused federal officers of triggering a dangerous escalation of the situation with abusive and unconstitutional tactics.

As he met with protesters on Wednesday, Wheeler himself was hit by tear gas, an incident he described as "flat-out urban warfare."

Trump, who is campaigning for re-election in November on "law and order," also announced on Wednesday a "surge" of federal agents to crime hotspots including Chicago, following an increase in violence in the nation's third-largest city.

Federal agents deployed there will partner with local law enforcement, not riot control forces as seen in Portland.

Local officials have warned they would draw the line at any Portland-style deployment.

READ MORE: US should ensure right to protest for demonstrators and media: UN 

Source: AFP