PARIS (Reuters) - French banks BNP Paribas (BNP) and Credit Agricole are conducting internal inquiries into U.S. dollar payments to check whether they are potentially in breach of American sanctions, the banks said on Monday.

Neither would confirm whether the inquiries concerned U.S. sanctions against Iran, which have led to investigations at rival banks such as UniCredit and RBS and have already cost Standard Chartered a hefty fine.

"We are conducting an internal review," said a spokesman for BNP, citing a disclosure from its 2011 annual report that said the probe concerned "certain U.S. dollar payments involving countries, persons and entities that could be subject to U.S. sanctions", adding that the bank had spoken to American regulators.

Credit Agricole, which used similar wording in its own annual report, is also reviewing payments linked to countries and entities potentially subject to U.S. sanctions, a spokeswoman said. "The review is ongoing," she said.

Societe Generale, France's No.2 listed bank, does not refer to any such review in its own annual report. The bank stopped all operations with Iranian entities from February 2012 and has returned its banking license to the central bank of Iran, a spokeswoman said. (Reporting by Lionel Laurent and Christian Plumb; Editing by David Goodman)