Scott Olsen suffered a fracture on his skull when he was hit by a projectile fired by local American police forces during an Occupy Oakland protest

An American marine veteran of the US war on Iraq is to undergo a brain surgery after suffering life-threatening injuries during an anti-Wall Street protest in Oakland, California, where police officers brutally attacked protesters on Tuesday.

The 24-year-old former US soldier, Scott Olsen, suffered a fracture on his skull when he was hit by a projectile fired by local American police forces during an Occupy Oakland protest, the Associated Press reported.

"He was standing perfectly still, provoking no one," said Raleigh Latham, an Oakland filmmaker shooting footage of the confrontation between police and hundreds of Occupy Oakland protesters.

While doctors await Olsen's brain swelling to ease to operate on it, his injury has intensified the focus of national attention on Occupy Oakland in the aftermath of repeated police tear-gassing of protesters Tuesday.

Tuesday's clashes appear to have re-energized the US Occupy Movement, as Oakland protesters have vowed to shut-down the city next Wednesday, to protest police brutality.

They have called on workers and students to join the protests and vowed to march on all banks and corporations who do not close down for the day.

The “Occupy Oakland” protests are part of the “Occupy Movement” in the US against pervasive economic inequality in the country, which has gone global and is now in its sixth week.