The U.S. Securities and Exchange Commission wrote to oil companies that did business in Iran to disclose any commissions that were paid to the nation’s government. The list of companies included Total SA and Norsk Hydro ASA, according to a Wall Street Journal report.

"We have looked at your disclosures over the past two to three years and you have disclosed operations in Iran," stands in SEC message, according to a person who has seen the letter.

"We want to know if you have paid commissions on contracts to the Iranian government," says the message from regulators, adding: "The object of this inquiry is to help you to improve your disclosures" in SEC filings.

The correspondence was dispatched by the SEC’s corporate finance department and may represent a routine request for information without suspicion of any wrongdoing on the part of oil and oil-service companies that were contacted. Recently, the SEC has increased its global reach by enhancing its scrutiny of companies that were included in Iranian operations.