Drone flying in sky
Drone flying in sky Chris Ison

Drones send four prisons into lockdown

DRONES have invaded the air space above four high-security Queensland prisons, forcing them all into lockdown.

Authorities are investigating Sunday's incidents but have determined no drugs or other banned items were dropped into the grounds of the jails.

It's believed at least three drones were in the air above the Brisbane Correctional Centre, Brisbane Women's Correctional Centre, Wolston Correctional Centre and Arthur Gorrie Correctional. The four sites are close to each other, southwest of Brisbane.

Queensland Corrective Services Commissioner Peter Martin described the security threat as an "ill-conceived stunt".

"Drones are a real threat when used to introduce contraband into our prison system or to aid in the escape of prisoners," he said in a statement today.

Prison authorities across Australia have been working out how to deal with drone incursions. A trial to detect drones at the Woodford Correctional Centre, north of Brisbane, is already underway.

The month-long trial aims to detect the location and speed of drones, and intercept communications with the unmanned craft.

If it's successful it will be rolled out to other sites in Queensland. All four prisons have since resumed normal operations.