Device at former SA bikie club explosive

A homemade device found outside a former bikie clubhouse in Adelaide's inner-west had the potential to explode, police have revealed.

The device was discovered in Thebarton on Thursday morning right outside a 24-hour gym that used to be clubrooms for the Mongols Morotcycle Club.

Police closed Dalgleish St and nearby roads while the bomb squad inspected the suspicious item, which appeared to be a bottle with pellets inside.

Superintendent Scott Fitzgerald says those officers determined the device, made of household substances, had the capacity to explode but made it safe.

He says an investigation into the incident will look at whether it is linked to outlaw motorcycle gangs or an earlier arson attack on the gym in August.

"It has all the hallmarks of outlaw motorcycle gang-related violence that we've seen in the past," he told reporters on Thursday.

"We're not discounting any line of inquiry and certainly not focusing on that line. However it certainly forms a large part of our investigation."

He said it was believed the device was dropped off at the gym's front door sometime between 5am and 6am on Thursday and police were appealing for any witnesses.

A small number of people were evacuated from the gym when the item was discovered.