Australia’s nuclear safety agency said on Tuesday it had joined the search for a small radioactive capsule missing somewhere in the outback, sending a team with specialized portable and car-mounted detection equipment.

Authorities have now been searching for a week for the capsule, which is believed to have fallen from a truck that made an 870-mile journey in Western Australia. The loss has triggered a radiation alert for much of the vast state.

The capsule, part of an indicator used to measure the density of iron ore feed, had been entrusted by Rio Tinto Ltd to a specialist contractor for transport. Rio apologized Monday for the loss, which occurred sometime in the past two weeks.

The Australian Agency for Radiation Protection and Nuclear Safety said it was working with the Western Australian government to locate the capsule. He added that the Australian Nuclear Science and Technology Organization has also sent specialists in radiation services, as well as detection and imaging equipment.

The truck traveled from Rio’s Gudai-Darri mine north of Newman, a small town in the remote Kimberley region, to a storage facility in suburban Perth, a distance greater than the length of Britain.

State emergency officials on Tuesday issued a new warning to motorists along Australia’s longest highway to use caution when approaching search parties as vehicles carrying radiation detectors travel at low speeds. .