A mining company, Rio Tinto, apologized on Sunday for the loss of a highly radioactive capsule over a 1,400-kilometer (870-mile) stretch of road in Western Australia.

The capsule, which contains a small amount of radioactive cesium 137, is about 6 millimeters in diameter and 8 millimeters tall. It was part of a device believed to have fallen from a truck while being transported between a desert mine north of the town of Newman and the city of Perth.

The device was last seen on January 10, and he truck transporting the capsule arrived at a Perth depot on January 16.

However, emergency services were notified of the missing capsule on Wednesday, and the information was only made public on Friday.

Rio Tinto 'sorry for the alarm'

According to the chief executive of the mining giant Rio Tinto Iron Ore, Simon Trott, the company was taking the incident very seriously.

"We recognize this is clearly very concerning and are sorry for the alarm it has caused in the Western Australian community," Trott said.

"As well as fully supporting the relevant authorities, we have launched our own investigation to understand how the capsule was lost in transit," he added.

Trott also said the contractor was qualified to transport the device and it had been confirmed being on board the truck by a Geiger counter prior to leaving the mine.

Extensive search and lack of equipment

Western Australia emergency services have called on other Australian states and the federal government for support finding the capsule as they lack equipment.

The search included people scanning for radiation levels from the device along the roads used by the truck, with authorities warning that the entire 1,400-kilometer route may need to be searched.

Because the pod is tiny, people have been warned it may have unknowingly become lodged in their car's tires.

The cesium 137 ceramic source, commonly used in radiation gauges, emits dangerous amounts of radiation, equivalent of receiving 10 X-rays in an hour. It could cause skin burns and prolonged exposure could cause cancer.

dh/dj (AP, dpa, Reuters)