The French economy minister is urging U.S. authorities to be "fair and proportionate" when deciding on a potential multibillion-dollar fine against France's largest bank over its activities in countries Iran, Sudan and Cuba.

Arnaud Montebourg, speaking on BFM television Monday, said the U.S. has an unfair advantage in the global "economic war" because of a law allowing prosecution of foreign companies for activities outside American soil.

BNP Paribas SA is under investigation for currency transactions through its New York office for clients in Iran, Sudan and Cuba in violation of U.S. trade sanctions.

Montebourg would not comment on a Wall Street Journal report that BNP and U.S. prosecutors have agreed to a deal involving a fine of $8 billion to $9 billion.

BNP's shares fell Monday morning in Paris trading.