Western Australia radioactive capsule missing: Search continues for unit ... trends now

A dangerous radioactive capsule was missing for two weeks before anybody realised, officials have admitted.  

Authorities have launched an investigation to determine how the tiny but potentially deadly radioactive capsule got lost as it was transported from a West Australian Rio Tinto mine to Perth.

The eight by six millimetre unit is believed to have fallen off the back of a truck on its 1400 kilometre journey from Newman to a depot in the Perth suburb of Malaga.

Emergency services claim they are hampered in their efforts to find the capsule by a lack of equipment and have called on the Commonwealth and other states to provide more, including units that can be fitted to a vehicle. 

The Department of Fire and Emergency Services has deployed teams with handheld radiation detection devices and metal detectors along 36km of the busy freight route.

Superintendent Darryl Ray said they were concentrating on populated areas north of Perth and strategic sites along the Great Northern Highway.

'What we're not doing is trying to find a tiny little device by eyesight' he told reporters on Saturday.

'We're using the radiation detectors to locate the gamma rays.'

In a disturbing twist on Friday, Department of Fire and Emergency Services Superintendent Darryl Ray admitted no one noticed the dangerous radioactive capsule was missing for more than two weeks. 

Authorities are also using the truck's GPS data to determine the exact route the driver took and where it stopped after it left the mine on or about January 10.

But there are concerns the solid capsule may have already become lodged in another vehicle's tyre and potentially be hundreds of kilometres away from the search area.