The Turnbull Government is in the final throes of weighing up the sale of the communications network that connects all its departments, in the midst of a storm over foreign investment in strategically important assets.
The Intra Government Communications Network (ICON) was established in 1991, with five kilometres of cables connecting two Department of Foreign Affairs and Trade buildings in Canberra.
It now provides 88 different government agencies and departments with "dark fibre" channels for secure communications across 400 buildings in the nation's capital.
In February, Finance Minister Mathias Cormann announced a scoping study to look into the future management and operation of ICON and to assess its likely sale. No decision on the sale was to be made until the Government received the study, due in the first half of the year.
Finance department officials told Senate estimates earlier this year there were 1,582 individual cables making up an 882-kilometre ICON network that includes about 160,000 kilometres of fibre.
The first assistant secretary of the Finance Department, John Sheridan, told the hearing the network costs $8 million a year to run.
He detailed the sheer scale of the network, which has 516 points of presence in 2,040 pits around Canberra.
"It's physically rated at 'protected' and agencies can use that to connect, rather than use commercially provided cables," he said.
Current DFAT secretary Peter Varghese refused to answer questions about the network's potential sale at an event in Canberra on Monday.
"It's not an issue I want to go into today," Mr Varghese said.
'Dark fibre' leak could compromise national security
According to Government security guidelines the "protected" security classification means its compromise "could be expected to cause damage to the National Interest, organisations or individuals".
Mr Sheridan said the network was about a tenth of the cost of commercial cable.
"We call it dark fibre... so we just provide the link. They [departments] run over whatever communications they want to," Mr Sheridan said.
