​An urgent search was underway in Western Australia on Saturday after a tiny radioactive capsule was reported to have gone missing while being transported from a mine.

​The 8 millimeter by 6 millimeter silver capsule, which is used in mining operations, has been unaccounted for since mid-January, emergency services said.

It contains the radioactive substance Caesium-137, according to Western Australia's Department of Health.

The capsule is believed to have fallen off a truck while being moved to a storage facility.

Caesium Capsule Beside Coin
The capsule beside a coin for comparison. (DFES)

Health officials have warned it can cause radiation burns or sickness if handled.

Fire and emergency services said the capsule was lost between the remote town of Newman and the suburbs of northern Perth, a distance of about 1,400 kilometers (870 miles).

Officials have warned the public not to handle the capsule if found and to contact emergency services.

"The concern is someone will pick it up not knowing what they are dealing with," said Dr Andrew Robertson, chief health officer for Western Australia.

A fire service spokesman said they are prioritizing populated areas during the search, which could take weeks.

Authorities were only alerted on Wednesday after the company responsible for the capsule realized it was missing, he added.

© Agence France-Presse