The bomb squad robotic unit was transported to Mount Isa last week to help with the search, but Mount Isa Police Inspector Trevor Kidd said they never got to use it in the ore pass because the terrain proved too difficult, and the chute was too dark, for it to operate properly.

Last Friday police announced the search for Mr Kelly was now a recovery mission after receiving advice about the worker’s ability to survive underground since last Wednesday.

It is believed Mr Kelly fell down an ore pass - an underground shaft, roughly the same height as the Eiffel Tower, where loose ore from all levels of the mine is dumped to be crushed and conveyed to the surface at the lowest level of the mine.

Insp Kidd said the time between Mr Kelly’s disappearance on Wednesday and the cease of operations at the ore pass that afternoon was considered during yesterday’s discussions.

“We don’t believe he’s on top of the ore face,” he said.

“You can stand on the edge and check the top of the ore face but it’s very difficult.”

“You can’t just get down there and start sifting through it so you only have a visual and pieces of this pass are constantly falling in and breaking off.

The ore pass will remain closed until the recovery mission is complete.