Standard Chartered (STAN.L) was still reviewing if some of its clients were Iranian or Iran-connected entities in 2013, the Financial Times said, saying it had identified transactions that could put the bank at risk of more U.S. penalties.

The London-listed bank's shares were down 2.4 percent at 705.6 pence by 0300 EDT, underperforming a flat European banking index .SX7P.

Standard Chartered paid U.S. authorities $667 million in 2012 after breaking sanctions, including with Iran, and was last year fined another $300 million after shortcomings in its monitoring were uncovered. In December U.S. authorities extended their monitoring of the bank's sanctions compliance by three years, partly due to "possible historical violations" of U.S. sanctions laws that took place after 2007.

The FT said on Monday it had seen documents suggesting that after the 2012 settlement Standard Chartered "was still internally reviewing its client list and was unable to determine in certain cases whether customers were Iranian or not."

The newspaper said it had identified transactions involving Iran that could put the bank at risk of severe penalties ranging from further fines to suspension or loss of its crucial U.S. dollar clearing license.

Standard Chartered was not immediately available to comment. The FT quoted the bank as saying following its decision to close its Iranian business in 2007 it had "a number of legacy obligations including dormant accounts, outstanding loans and trade-finance agreements. Those legacy obligations have been handled in an appropriate manner in non-U.S. currencies and since 2007 it has been the group's policy not to pursue any new business with known Iranian entities."

The bank has said it is cooperating with the investigations by U.S. authorities.

By Reuters