A registered Democrat and Bernie Sanders supporter has been beaten up by left-wing militants for carrying an American flag at a protest rally.

Paul Welch, a 38-year-old self-described 'slightly progressive leftist' took the flag to the Portland rally earlier this month in a bid to 'take it back' from the conservative movement, according to Oregon Live.

The Oregon man joined hundreds of counter-protesters gathered at City Hall when he was approached by two Antifa activists who demanded he drop the'fascist symbol', ripping it from his hands and leaving him recoiled on the ground with a bloody wound to his head.

Paul Welch, 38, a registered Democrat and Bernie Sanders supporter, was protesting a right-wing rally in Oregon when he was attacked by his own group for carrying an American flag

Two Antifa activists demanded he drop the 'fascist symbol', ripping it from his hands and leaving him recoiled on the ground with a bloody wound to his head

The Anifa members, dressed in black and wearing protective shields, are seen hauling the flag from Paul's hands when a man is heard shouting: 'Let go of the flag!'.

Another masked counter-protester is then seen approaching, striking him from behind with a weapon hidden in black fabric.

With one final blow to the back of the head, Paul falls to the ground where he lies cowering with his hands over his head.

In the video, uploaded by Mike Bivins who was also at the scene, the offender is seen casually walking away.

With one final blow to the back of the head, Paul falls to the ground where he lies cowering with his hands over his head

A group of volunteer street medics rushed to Paul's aid, taking him to an urgent care clinic

Paul was given four staples to close a three-inch gash on the back of his head (pictured) and spent two days recovering from a concussion

'I was watching the blood pour out of his head and into the street,' Mike Bivins captioned the video he posted over Twitter.

A group of volunteer street medics rushed to Paul's aid, taking him to an urgent care clinic.

He was given four staples to close a three-inch gash on the back of his head and spent two days recovering from a concussion.

Paul said he didn't come to the protest as part of any one particular group.

I was just protesting outsiders coming here for their tacitly fascist event,' he said.

Paul (above) said he didn't come to the protest as part of any one particular group. I was just protesting outsiders coming here for their tacitly fascist event,' he told Oregon Live

'I had felt like showing that a liberal, free Portland ... is much more American and much more numerous and strong than any of these interloping groups,' he said.

'It's kind of like you're playing into your opponent's hand when you do that sort of thing. That's not what I was there for.'

A police report was filed and authorities have said they are investigating the incident.

At least three people were hospitalized after clashes between right-wing demonstrators and Antifa protesters during the Portland rally.