Sydney 'jailbreak' to be probed

An investigation is underway into how a female prisoner became stuck in razor wire on top of a fence at a Sydney jail during what appeared to be an escape attempt.

The 36-year-old Silverwater Women's Correctional Centre inmate had to be rescued using a cherry picker on Friday afternoon after she managed scale the fence but became tangled in the wire.

She was treated for minor injuries amid suggestions the incident may not have actually been an escape attempt, but a form of protest over access to medication.

Public Service Association spokeswoman Nichole Jess, who has worked at the facility for nearly three decades, said staff initially saw the woman on a roof and responded immediately, following her from the ground.

"Certainly that needs to be looked at, the security aspect of how she was able to get to that height quite quickly," Ms Jess said.

Prison authorities will review CCTV footage as part of their investigation into the incident.