A tiny highly radioactive capsule that was lost last month was finally found on the side of a road in Australia

• Australian authorities have located a missing radioactive capsule after a six-day search.
• The dangerously radioactive object fell off a mining truck in January, sparking a massive hunt.

Authorities in Australia have succeeded, after a six-day search, in locating a dangerously radioactive capsule that fell off a truck last month.

The find, announced on Wednesday, concluded a high-stakes hunt along 870 miles (1,400km) of highway that one official likened to searching for a "needle in the haystack."

The capsule was part of mining equipment — an industral gauge – that was being transported from a desert mine to Perth on January 10. Emergency services were first notified it was missing on January 25, nine days after the truck arrived, the Associated Press (AP) reported.

Though tiny, the capsule emits powerful radiation, the equivalent of receiving 10 x-rays an one hour, with prolonged exposure leading to risks of cancer, the AP reported.

The roadside search area for the pea-sized capsule was roughly equivalent to the length of the total east-to-west span of Nebraska, Iowa and Illinois.

"When you consider the scope of the research area, locating this object was a monumental challenge," Emergency Services Minister Stephen Dawson said at a press conference.

"The search groups have quite literally found the needle in the haystack," he added.

Authorities had earlier asked drivers who travelled along the highway in that period to check their tire treads in case the capsule had become lodged there, the Australian Broadcasting Corporation reported.

In the end it was found two meters from the side of the Great Northern Highway, just south of Newman, a small town in the north of the region.

A vehicle carrying specialist sensor equipment picked up the capsule's radiation, allowing investigators with portable devices to finally hone in on it, Fire and Emergency Services Commissioner Darren Klemm said.

A 20-meter (66 ft) "hot zone" has been set up around it, he added.

The Western Australian Radiation Council has launched an investigation into how it was lost, Dawson said.

Rio Tinto Iron Ore, which was transporting the capsule, apologized for the debacle and thanked the search crews in a statement on Wednesday, with CEO Simon Trott saying: "The fact is it should never have been lost in the first place."

The company is starting its own investigation, the statement said.