Iran has reached a deal to buy 100 Boeing planes, the head of Iran's Civil Aviation Organisation has told state media.
Ali Abedzadeh added the two sides are waiting on approval from the US government.
"Of the 250 [passenger] planes in Iran, 230 have to be replaced," Abedzadeh told Mehr News Agency.
He added that no timeline could be given until approval has been given from the US Treasury Department.
A Boeing spokesperson said: "We have been engaged in discussions with Iranian airlines approved by the US government about potential purchases of Boeing commercial passenger aeroplanes and services.
"We do not discuss details of ongoing conversations we are having with customers, and our standard practice is to let customers announce any agreements that are reached. Any agreements reached will be contingent on US government approval."
Preliminary talks got underway in April, with Boeing in talks with Iranian airlines to sell planes to the largely untapped marketplace.
In April, Airbus signed a $27bn deal to sell 118 plans to Iran.