Mining giant "sorry" over lost radioactive capsule in Australia.

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Mining giant Rio Tinto says it is working with authorities to try to find a radioactive capsule that went missing in Western Australia this month.

"We recognise this is clearly very concerning and are sorry for the alarm it has caused," the firm told the BBC.

The casing contains a small quantity of radioactive Caesium-137, which could cause serious illness if touched.

It was lost between the town of Newman and the city of Perth, a distance of roughly 1,400km (870 miles).

"As well as fully supporting the relevant authorities, we have launched our own investigation to understand how the capsule was lost in transit," Rio Tinto's Iron Ore chief executive Simon Trott said in a statement.

"As part of this investigation we are working closely with the contractor to better understand what went wrong in this instance," he added.