Standard Chartered has released a statement saying that the bank was already conducting a review over its Iranian transactions and the Group had been in touch with the New York State Department of Financial Services (DFS).
Standard and chartered said:
"The Group does not believe the order issued by the DFS presents a full and accurate picture of the facts.
"The analysis, that the Group shared with all the US agencies, demonstrates that throughout the period the Group acted to comply, and overwhelmingly did comply, with US sanctions and the regulations relating to U-turn payments.
"As we have disclosed to the authorities, well over 99.9% of the transactions relating to Iran complied with the U-turn regulations. The total value of transactions which did not follow the U-turn was under $14m.
"The Group is engaged in ongoing discussions with the relevant US agencies. Resolution of such matters normally proceeds through a co-ordinated approach by such agencies.
"The Group was therefore surprised to receive the order from the DFS, given that discussions with the agencies were ongoing. We intend to discuss these matters with the DFS and to contest their position.
"The Group takes its responsibilities very seriously, and seeks to comply at all times with the relevant laws and regulations. It is in this spirit we initiated this review and have engaged with the US agencies."
After accusations of money laundering on behalf of the Iranian regime, Standard Chartered's chief has said "sorry".
Shares in Standard Chartered have had an absolute savaging on the stock market. Dives like this are unusual, and serious for any company
It might not be a big name on our high streets but Standard Chartered is one of the biggest names in banking.