The ACT has been the source of most jobs marked for relocation or moved under plans to "decentralise" the public service since 2013, new figures show.

Only 7 positions are leaving Melbourne's centre and 37 jobs have shifted from Sydney city.

Population centres Adelaide, western Sydney and Brisbane are among the beneficiaries of "decentralisation", despite the Coalition's promise it would move public servants to struggling regional areas.

Adelaide is receiving hundreds of Commonwealth roles, according to the government's tally of decentralised jobs, prompting calls for a greater focus on regional cities.

The numbers tabled in Senate hearings by the Infrastructure Department show 14 agencies have relocated or will move staff from the ACT under the push to decentralise the public service.

Among employers shifting the most jobs from Canberra are the Employment portfolio's Unique Student Identifier (40 positions), the National Indigenous Australians Agency (35) and the Infrastructure portfolio's regional programs branch (24).

Decentralisation Minister Mark Coulton said the relocations would leave jobs growth in the ACT unharmed while growing economic activity in rural Australia.

Locating regional offices of departments in regional areas gave staff a better understanding of local issues, he said.

Most of the jobs counted in the government's tally of 1700 decentralised positions since 2013 have been newly created and marked for "regional" locations.

Canberra has been the source of at least 403 jobs moved, or soon to be relocated, by the Coalition government.

The number could be higher, as it doesn't include agencies that are growing their regional offices with both new and relocated jobs, and who are yet to determine the number moved from the ACT.

ACT Liberal senator Zed Seselja and NSW Nationals leader John Barilaro have said the Coalition's decentralisation agenda is "incorrectly focused" on Canberra.

Former Defence Department and ASIO chief Dennis Richardson has also called for efforts to relocate public service jobs to target Australia's largest capital cities instead.

The ACT has Australia's largest workforce of federal bureaucrats, numbering 55,200, or about 38 per cent of the public service. Sydney's city and inner south have about 10,200 public servants, and inner Melbourne has another 14,500.

Federal insurer Comcare expects to have 30 more staff based outside Canberra, but hasn't decided how many of these will be new positions or roles moved from the ACT.

The Australian Financial Security Authority will move 15 roles to Perth, Hobart and Brisbane through "natural attrition", hiring new staff in these cities when its public servants leave jobs in Canberra, Sydney and Melbourne.

Twenty Australian Space Agency jobs will leave the ACT for Adelaide.

Six agencies are growing their presence in the South Australian capital, which will have 325 more public servants since 2013 through decentralisation.

Regional Capitals Australia chairwoman Samantha McIntosh said smaller state capitals like Adelaide and Perth needed to attract more residents and diversify their economies, but should not be considered regional.

The group's members include regional cities across Australia.

They needed public service jobs for more economic opportunities, and to aid better service delivery and support population growth, Cr McIntosh said.

She praised decentralisation as a "great initiative" and said some of the group's members, including Dubbo, Wagga Wagga and Coffs Harbour, had benefited.

"These cities welcomed the investment of new jobs and residents," Cr McIntosh said.

"Regional Capitals Australia will advocate that the government continues this initiative, all our member cities are capable of providing access to a great affordable lifestyle for any person or family who is relocated."

Community and Public Sector Union national secretary Melissa Donnelly said people living in rural and regional Australia deserved "security, opportunity and dignity" at work.

"If the government cares at all about the kinds of lives people in rural and regional Australia can hope for, they should be prioritising new jobs in places where unemployment is hitting the hardest," she said.

"Public sector jobs are incredibly important in many of these communities, having an important multiplier effect in addition to directly offering a source of stable and secure employment."

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The union does not support the relocation of existing jobs, which it calls "extremely disruptive and difficult for workers and their families".

"If the government is serious about supporting regional employment, there's a really simple solution - reverse the cuts they already made to regional jobs, and set up new jobs in the regions so that the public service can provide the services communities desperately need," Ms Donnelly said.

The Australian Maritime Safety Authority's plan to lift its regional presence by 69 jobs will grow employment in Coffs Harbour.

The agency has moved 11 positions from Canberra since July, and created eight new positions, in growing its regional staff numbers.

Labor's regional development spokeswoman Catherine King called the decision to move public servants from Canberra to other mainland capital cities "politically motivated".

"The Liberals and Nationals talk a big game on decentralisation but they've actually cut front line public servants in many regional communities from Centrelink and the ATO," she said.

"Rather than the politically motivated step of moving some public servants from Canberra to mainland capital cities, Scott Morrison needs to outline a real vision to build our regional economies and with that greater regional public services."