Iran has received far less money than expected as a result of a nuclear deal and cessation of sanctions, with just $3bn (£2bn) reportedly released since January 2016.
Iran was estimated by the US Treasury at the beginning of year to receive more than $50bn (£34bn) from money that had been held in overseas banks from the sale of oil. Some of those funds were committed to infrastructure projects.
US secretary of state John Kerry told delegates at an evening hosted by pro-Israeli group J Street that the figure released from Iran's assets to date was significantly lower than expected. However, it is unclear how much money is yet to be released to the country.
"Remember the debate over how much money Iran was going to get?" AFP reported Kerry as saying. "Sometimes you hear some of the presidential candidates putting out a mistaken figure of $155bn. I never thought it would be that. Others thought it would be about $100bn, because there was supposedly about $100bn that was frozen and so forth."
Kerry added that the US government had calculated the money Iran was set to receive at around $55bn, but told the J Street delegates the country had seen just $3bn since the nuclear deal came into effect.
His comments come as relations between the US and the Islamic republic are in a state of flux, with the US trying to ensure the Iran doesn't act outside of the agreed terms of the sanction cessation deal. There is mounting pressure on the US government from Republicans, many of whom disagree with the nuclear deal.