The Immigration Department has been criticised for a $255 million plan to move public servants to a new office ten minutes away.

The department has launched one of the most expensive fit-out and relocation projects in public service history, with a new four building precinct set to have “a unified watch floor, situation rooms, briefing rooms, incident rooms, operations planning rooms and intelligence support rooms”.

The new headquarters will boast an “armoury” for the 957 Border Force and Immigration staff that carry weapons.

Immigration employs about 6,000 public servants in Canberra.

The relocation is intended to cut the number of Immigration Department buildings in Canberra from 12 to five, saving close to $324 million in leasing costs over 30 years.

Finance Minister Mathias Cormann last year approved the quarter-of-a-billion dollar plan to move staff 9 kilometres away, which Labor Senator Kim Carr says is an unnecessary burden on the taxpayer.

Senator Carr says the department should look at buying the buildings, rather than renting them.

Department officials say did not consider whether buying the building would have been cheaper.

“If you are going to be in the building for nearly 30 years and it's going to cost you nearly $3 billion, how much would it cost to build a building and not pay the rent?

“With this amount of money going to a private owner, surely you would have considered what it would cost the Commonwealth to purchase the building itself,” Senator Carr asked.

Immigration Department secretary Michael Pezzullo joked to reporters about bringing his own chair and washing his own bathroom towels to save money.

Immigration officials say the average cost per square metre at the Canberra Airport precinct will be $2,053, which Senator Carr criticised for being “substantially above” the standard Government spend of up to $1,800 per square metre.