A pest inspector will assess the extent of the damage this morning, however the fact the walls in one room crumble at a push indicates the infestation is well advanced.

Oxley Local Area Commander Superintendent Tony Jefferson inspected the station late last week and immediately called for a structural inspection and for the pests to be eradicated.

"The situation has got so bad the white ants are now coming out of the wall," Supt Jefferson said.

"If you push on the wall, you actually go through the skin, the paint work and into the timber."

At this stage the ants appear confined to the detective's room and have not spread into the cell area currently undergoing $500,000 worth of renovations.

Supt Jefferson said Police Properties knew the white ants were in the building through "a number of inspections" which began at least 12 months ago.

But the extent was only revealed last week when builders fired up jack hammers in the cell area at the opposite end of the building.

"It's disturbed the nest, the banging and the vibration has upset the white ants and they're on the move," Supt Jefferson said.

"The concern I have is, when was that inspection done and is the building safe."

"I want a structural engineer to say, 'I've examined the building and it's safe for people to work inside'."

The department has assured Supt Jefferson the building was safe and will send a building inspector to Gunnedah as soon as today.

"The evidence now is the ants have come out of the wall and are nesting outside, on the exterior walls and around lights and fittings," he said

"The staff are working away and the things are crawling on them," he said.

"They're not happy."

Supt Jefferson said he did not blame Police Properties which had a limited budget and was concentrating on the most urgent matter being the renovation of the cell and custody area.

He said area affected by termites was to be renovated down the track but it might now have to be rebuilt.

Asked whether it would have been a cheaper option overall to move into another premises or build a new one, Supt Jefferson said he did not know.

"If the infestation is that bad, we can say don't renovate that part, consider the options and the cost benefit of public money and we would then lobby for a new facility that would last us into the future," he said.