WA mine raids net one cannabis stash

Almost 1,200 WA mine workers were searched by drug detection dogs as part of an ongoing police operation, but only a single stash of cannabis was found.

A police raid on Gina Rinehart's Roy Hill iron ore project in Western Australia's Pilbara has resulted in just one drug seizure.

Police said a drug detection dog was used to search 695 workers and their luggage as they arrived on site by bus.

The dog had six "indications", which suggested that illegal drugs may be present, but only one amount of cannabis was found after a subsequent search.

At a BHP Billiton mine, 495 workers were screened and there were seven dog indications, but no seizures.