Staffing at the SA Department of Communities has been doubled as workers fight an incredible backlog of applicants for working with children checks.

The authorities say there have been close to 150,000 applications this year alone, equal to about 10 per cent of the state’s population.

Background checks are a legal requirement for anyone wishing to work with children, but staff also have to deal with checks for jobs and volunteer roles to ensure people convicted of certain offences are kept out.

“The demand is huge, so we've more than doubled our staff in the last six months and are still trying to recruit another 21 to get on top of the delays,” the SA Department for Communities and Social Inclusion's Peter Bull has told the ABC.

“We've halved that backlog in the last six weeks. Our target is to try to get 95 per cent [of applications] done within 30 business days.”

Mr Bull said staff often had to sift manually through hard-copies of records, as electronic databases are incomplete, and even then it is not a simple process.

“Some [applications] can be many months if they're complex in terms of name matches and considering the nature of some of those offences and whether they pose a risk to children,” he said.

“They get escalated to a series of complex assessment panels.”

Mr Bull said an online application system would start operating later this year.

The SA Council of Social Service has described the screening process as appallingly slow, a sentiment with which Family First MLC Robert Brokenshire agrees.

“In the Northern Territory for child protection clearances they have a two-week turnaround and in Queensland they have a blue card policy which streamlines the whole thing and it works very efficiently,” he told the ABC

“I've met people from Queensland and that blue card works extremely well, the technology can check on them if there's any problem. It's a bit like a driver's licence.”