A man walking to freedom from a South Australian prison has allegedly been violently attacked with a hammer and a metal pole by bikies in the foyer of the building.

The man was leaving the Yatala Labour Prison in Northfield on Monday afternoon when two masked men stormed the entrance, allegedly bashing him as he cowered against a security door.

The victim suffered injuries to his head, upper body and legs before the men fled.

He was treated in hospital before being released that day.

One man has been charged over the alleged attack. (SA Police/Supplied)

Vision of the violent assault at the state’s highest security vision was released by South Australia Police today after a 22-year-old Blakeview man was charged over the attack.

The accused man, who police say is a member of the Comancheros bikie gang, has been charged with aggravated assault intentionally causing harm, failing to truthfully answer questions and possessing prescription drugs.

The second alleged offender remains on the run.

The victim had walked free from the state's highest security prison moments before he was allegedly bashed. (SA Police/Supplied)

South Australian police have slammed the brazen nature in which the attack occurred.

"The disregard those involved with outlaw motorcycle gangs have for the safety of the community when committing such acts of violence comes as no surprise, nor their preparedness to do so in public places,” Detective Chief Inspector Kym Hand said.