Iran has blamed the plunge in the currency on what it says is a foreign conspiracy.
Mr Cohen, undersecretary for terrorism and financial intelligence, added in remarks on a visit to Britain's Chatham House think-tank that Iran had the ability to "relieve the pressure its people are feeling" by resolving concerns over its nuclear work. "What in particular has sparked the most recent precipitous decline in the rial, I'm not in a position to say," he said yesterday. However he added it was "in significant part due to the Iranian Government's own mismanagement of its economy and it is in part due to the effect of sanctions". He added: "The Iranian leadership has within its capacity the ability to relieve the pressure its people are feeling."