Thirty labour hire workers will be used in some Centrelink offices in Queensland, South Australia and Western Australia in what is believed to be self-managed support advisor roles from next month. This person generally greets people as they enter Centrelink offices and often directs them to using computers and phones in the offices.

The move is another step in increasing use of labour hire at the agency, following on from the announcement that 1500 call centre roles would be outsourced to Serco, Stellar Asia Pacific, Concentrix Services and DataCom Connect.

It had also previously been announced that 1000 staff from labour hire firms would be deployed at Centrelink offices around the country, and a pilot program with Serco with 250 call centre staff means 2750 contractors have been hired since last year to work at the agency. It's believed the trial is part of existing labour hire contracts Human Services has with private companies.

A Department of Human Services spokeswoman said the 30 staff members were additional staff.

"There are no job losses associated with the move," the spokeswoman said.

The main public sector union is worried that members of the public will be dealing with staff members who aren't employed by the government.

"The CPSU is seriously concerned that labour hire workers will now be the first port of call for customers walking into a Centrelink office, instead of permanent members of staff. We want Australians to be served by experienced and properly trained staff members," Community and Public Sector Union deputy secretary Melissa Donnelly said.

"The job might sound easy but dealing with clients who may be agitated or distressed as they walk into an office can be very difficult, and could pose a risk to the safety of the workers."

It's not yet clear how workloads will be managed in a role that was previously shared among Centrelink staff throughout a shift.

“Experienced Centrelink staff are able to manage that, but it’s going to be much harder for labour hire workers who don’t have the same experience or background. This is bad news for those workers and bad news for members of the community who are trying to access services," Ms Donnelly said.

The union has previously called for a complete end to the use of labour hire workers in the public service, and believes the average staffing level cap has contributed to the decision to trial labour hire workers in frontline roles. Nearly 1300 roles at the Department of Human Services were cut in the last budget, following on from 1200 cut in the budget before.

"Rather than imposing an arbitrary staffing cap on the public sector and forcing agencies to outsource to plug the gaps, the government should be investing in well-trained, fully supported employees who can offer our communities the services they deserve," Ms Donnelly said.

Labor spokesman for human services Ed Husic labelled the move a "slap in the face" for Centrelink workers facing losing their jobs in the lead up to Christmas.

"The staff that will make a commitment to public care are the ones that Centrelink has made a real commitment to - through secure, in house work," Mr Husic said.