The opposition said it hopes to make the country's bureaucracy an attractive workplace for the best and brightest minds while also reducing the brain drain.

It comes more than two years after a landmark review into the public service warned it was under enormous strain, recommending sweeping policy changes.

Labor public service spokesperson Senator Katy Gallagher said on Wednesday the recommendations from former Telstra chief executive David Thodey had been "largely mothballed" by Prime Minister Scott Morrison and had led to basic policy development being outsourced to the private sector.

If it wins government at the next election, which is due before the end of May, the opposition has promised it would remove the average staffing level cap, audit the usage of labour hire across the sector, commit to improving job security by limiting fixed-term contracts and address pay gap inequalities between agencies.

Senator Gallagher said the first step was to give people a reason to join the public service, and to keep them in it.

"The job of reversing the brain drain must start by valuing, respecting and investing in the APS's biggest asset - its people," she said.

"The APS should be a place which attracts the best and brightest minds from around the country and then retains them with exciting opportunities and clear career paths."

While no agency claims responsibility for collecting the number of contracted workers across the public service, figures show up to 40 per cent of some department workforces are made up of labour hire.

The Department of Veterans' Affairs said it had 1000 labour hire staff in May last year, totalling about 37 per cent of its total headcount. It entered into $142 million worth of contracts for labour hire in the six months to December 2020.

The ACT senator said it would convert public servants hired under labour hire, casual or contract arrangements into ongoing permanent roles.

Back pay would also be considered for employees in agencies who hadn't been subject to pay rises consistent with other public service agencies along with other industries.

"The APS should also be investing in job security - not wasting money on excessive and expensive temporary labour-hire contracts," she said.

"Labor will focus on reducing the job insecurity which has become rampant across key agencies and conduct an audit of employment arrangements across the APS to ensure temporary forms of work are being used appropriately."

Labor said it believes the implementation of these policies will result in an increase of permanent jobs within the sector.

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The report by Mr Thodey, publicly released in December 2019, offered 40 recommendations to reform the public service's aging approach.

While the Morrison government welcomed the review, it knocked back many of the report's key recommendations, including a push to remove the staffing level cap, to make pay scales and conditions more consistent and a move away from labour hire reliance.

Finance Minister Senator Simon Birmingham has previously defended the public service's labour hire arrangements, adding they fluctuated each year for different agencies, depending on operational pressures, but were an effective and efficient measure.

"Labour hire has an important place in many areas of work, including for major transformational efforts as well as for roles that are seasonal, projects that are one-off and time sensitive, like those seen during the COVID-19 pandemic," he said.

"The budget process allows for the government to routinely scrutinise staff allocations to ensure they are optimal in the present environment, and to ensure any new pressures can best be met by reprioritising existing staff or by engaging new staff."

But Senator Gallagher said that way of thinking would be ditched in favour of a public service with built-in capability, which is less reliant on private sector talent.

"The last two years have thrust the APS into the public's line of sight in a way that we have not seen for many decades and the demands on the public service are only going to increase both in output and complexity as we grapple with the public policy challenges currently before us and the ones that lie ahead," she said.

"It is critical that the APS has the capability and people to respond to these challenges as it has proudly done for the past 120 years."