The US arm of Deloitte has been implicated in a scandal involving Standard Chartered Bank (SCB), which is facing allegations that it schemed with Iran to launder billions of dollars.
The bank is accused of devising a method of masking Iranian client transactions to bypass US money laundering defences and watered down an independent report into the bank's practices.
The New York State Department of Financial Services' order found the bank's actions left the US financial system "vulnerable to terrorists, weapons dealers, drugs kingpins and corrupt regimes", in which £160bn was hidden from US regulators between 2001 and 2010. The report also alleges that Standard Chartered was helped by its accountants Deloitte.
Business and finance journalist