Executives at Gina Rinehart's Roy Hill mine in Western Australia have asked the police to investigate an attempted poisoning at the mine's construction site in the Pilbara.
The company said in a statement that on December 15 that a contractor working at the site notice an "unusual discolouration" inside a piece of fruit from the mine site's dining hall.
Laboratory testing of the fruit has confirmed the presence of a dangerous chemical, although Roy Hill says the incident appears to be isolated, with no other reports of contamination of other food at the site.
Roy Hill chief executive Barry Fitzgerald the company has now handed the matter to the police.
"Our first and foremost priority is the safety and well-being of our people. We have tightened our food security as a means of ensuring no further incidents occur; and are working closely with the police in their investigation."
Roy Hill will be the crowning jewel in Gina Rinehart's mining empire, as it will be the first mine she will independently own and operate.
In March the project secured a massive $US7.2 billion financing package and production is slated to start late in 2015.
Around 2,500 people are involved in the building of the mine.