The casing contains a small quantity of radioactive Caesium-137, which could cause serious illness if touched.

It was lost between the town of Newman and the city of Perth in mid-January — a distance of roughly 1,400km (870 miles).

The public has been warned to stay away from the capsule if they see it.

It was being transported on a truck between a mine site north of Newman in the Pilbara region and the northeastern parts of Perth between Jan. 10-16 when it was mislaid.

Caesium-137 is a substance commonly used in mining operations.

The Department of Fire and Emergency Services (DFES) has said the capsule cannot be weaponized but could cause radiation burns and have other longer-term risks like cancer.

The object emits a “reasonable” amount of radiation, Dr. Andrew Robertson, the state’s chief health officer and Radiological Council chair, said.

“Our concern is that someone will pick it up, not knowing what it is,” he said. “They may think it is something interesting and keep it, or keep it in their room, keep it in their car, or give it to someone.”

The sites where the transportation began and ended have been searched and efforts are under way to figure out the exact route and stops that were made to narrow down the field of search.

Anyone who sees the object is asked to call the DFES and to seek urgent medical assistance if they think they have come into contact with it.