BHP Billiton, the world's largest mining company, has uncovered possible corruption at exploration projects.
The issue involved "interaction" with government officials, and details had been passed to the Securities and Exchange Commission (SEC), BHP said.
BHP did not say where the violations occurred, but said it was not China, where four staff at rival Rio Tinto were recently jailed for bribery.
BHP said that the projects concerned were "small" and no longer active.
The Anglo-Australian company said in a statement that it had "disclosed to relevant authorities evidence that it has uncovered regarding possible violations of applicable anti-corruption laws involving interactions with government officials".
"Accordingly, the company is co-operating with the relevant authorities, including conducting an internal investigation, which is continuing," BHP said.
Internal investigations
A BHP spokeswoman added later: "We're talking about a couple of relatively small minerals exploration projects, the last of which was terminated about a year ago on commercial grounds.
"Only after that, in August last year, did we get an inquiry from the SEC asking us to do some internal investigations, which we did commence at that point.
"We have recently uncovered some evidence we have given to the SEC, and we are involved in ongoing internal investigations and co-operating fully with the SEC on this issue," she said.
In March, four Rio Tinto executives were jailed by a court in China after being found guilty of bribery and industrial espionage.
BHP disclosed the news as it unveiled third-quarter production figures. Metals and coal production were down, with copper particularly hard hit.
Copper output was down 15% on the previous quarter, while iron ore fell 4%.
BBC News
