The Facial Verification Service, part of the federal government's new 'Capability' program, would be accessible by departments such as the Department of Human Services or the Australian Taxation Office.

The system would be used to provide a one-for-one match from a person's existing photo with any other government issued identities they may hold, rather than returning multiple potential matches.

The Attorney General's department said government agencies and private businesses would have to complete a privacy impact statement before given access.

"Organisations using the service would need to demonstrate their lawful basis to do so under the Privacy Act, and could only use the FVS where they gain a person's consent to use their images," a spokesperson said.

Surveillance expert Professor Katina Michael from the University of Wollongong said access should only be granted on a case-by-case basis, concerned the Capability could be linked to a person's metadata or even tax file number.

"What I can't understand is it's open at all times indefinitely," Professor Michael said.

"That is not professional. It's warrantless searching."

She also raised concerns about the private sector having access to the system.

"It's going to be bi-directional. This is a lovely symbiosis between government and industry. This is the only way that government can crawl their way into the data sets of Facebook and Google."

When originally launched in November, the FVS used photos captured by the Australian Border Force from passports or citizenship photos, and was only available to the Department of Foreign Affairs and Trade or the Australian Federal Police.

Earlier this month, the federal government announced it would establish the national facial recognition system drawing on issued identification from all Australian jurisdictions allowing FVS users to access state or territory databases.

The Capability now comprises three parts, the Document Verification Service, the FVS and the Facial Identification Service.

The FIS allows law enforcement to scan photos of unknown persons and match them with multiple government records.

"For example, it can be used to identify a suspected paedophile from child exploitation material, or to identify an armed offender from a still image taken from CCTV footage," a spokesperson said.

The spokesperson said there were no current plans to expand access to the FIS to government agencies or the private sector.

But Professor Michael was concerned the FIS would eventually be opened up to other agencies and the private sector.