ASIO Central office building.

ASIO Central office building. Photo: Jay Cronan

A half-filled bottle with wires attached to it caused a bomb scare at the new headquarters of the nation's most powerful spy agency this week.

The suspicious package was found at the site of the new ASIO building in Russell on Tuesday.

It prompted a quick response from general duties police and the specialist bomb squad.

The bottle was cordoned off, while officers assessed its potential danger.

Eventually, the bomb squad declared the bottle ''inert'' and the area was given the all clear.

Police say they do not know who was responsible for the bottle being placed outside the building.

The new ASIO office is expected to house about 1800 people.

It was due to be occupied progressively from February to March this year.

But ASIO said on its website that a staged move of staff was now expected to begin in August.

The spy agency will take possession of the building in April.

The building's construction, which is still unfinished, has been subject to numerous problems, including cost blowouts and work safety concerns.

Glass panels have fallen from above the building's main entrance and crashed to the ground.

A teenager fell nine metres from the building into its basement in 2011.

He lay there, unconscious and unnoticed, for up to 36 hours.