Melbourne: Australia's nuclear safety agency announced on Tuesday that it had joined the week-long search for a small radioactive capsule that had gone missing in the country's western region and had sparked a radiation alert.

The Western Australian government and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) are collaborating to find the capsule, according to a statement.

The capsule, which is thought to have fallen from a truck, was a piece of equipment that Rio Tinto Ltd. had hired a specialized contractor to transport in order to measure the density of iron ore feed. The loss, which could have happened at any time over the previous more than two weeks, was apologized for by the company on Monday.

In a statement, ARPANSA said that it had dispatched a deployment team with specialized car-mounted and portable detection equipment to assist in the investigation of the transport route connecting Perth and the Pilbara region. They will start operating on January 31.

Now that the truck has travelled more than 1,400 kilometres (870 miles), or the length of Great Britain, from north of Newman, a tiny town in the isolated Kimberley region, to a storage facility in Perth's northeast suburbs, authorities are faced with the daunting task of searching along that route.

Along with radiation specialists, the state's Department of Fire and Emergency Services is in charge of the search. According to ARPANSA, the Australian Nuclear Science and Technology Organisation (ANSTO) has also sent teams of radiation services experts, as well as detection and imaging tools, to help with the search.

The community will be safeguarded from radiation's harmful effects while efforts are made to find the missing source, according to ARPANSA. State emergency officials in Western Australia warned drivers on Tuesday along Australia's longest highway to use caution when approaching the search party.

"Along the Great Northern Highway, DFES and radiation specialists are conducting slow-moving north and southbound searches. Be cautious when approaching and when overtaking."

On January 12, the gauge was taken from the Gudai-Darri mine site of Rio Tinto. On January 25, when it was opened for inspection, the gauge was discovered to be broken, with one of the mounting bolts missing and screws from the gauge itself.

The radioactive capsule from the gauge fell out of the package and then out of a gap in the truck, all of which were brought about by vibrations from the truck, according to the authorities.