Yara International, one of the world's largest fertiliser companies, said it had uncovered "unacceptable payments" at its joint venture in Switzerland after an external investigation into possible corruption it initiated last year.
Yara said on Friday it had told Norwegian police about the findings, which follow last year's discovery of possible offences in connection with the establishment of Yara's Libyan Norwegian Fertiliser Company.
Yara has also been charged with suspected corruption involving a possible $1 million bribe in India during efforts to create a joint venture.
Norway's white-collar crime unit, Oekokrim, is still investigating these matters, Yara said.
"We will get to the bottom of this. Such breaches of Yara standards are unacceptable," said Yara's president and chief executive, Joergen Ole Haslestad, in a statement.
The company declined to comment further.
"The suspicions that have arisen concern serious offences and in general it is important for Oekokrim to get to the bottom of these types of affairs," public prosecutor Marianne Djupesland told Reuters.
"As of today it is too early to say where this will end up in the criminal sense. When it comes to the India and Libya cases, we have come far but there still remain a few issues," she said.
"I hope and believe that it will not take long before we can draw the line in this matter."