Iran has reached a deal to buy 100 planes from US plane producer Boeing, and the two sides are awaiting approval by US Treasury authorities, according to the head of Iran's Civil Aviation Organisation.

"The final obstacle in this area are only the permits from the US Treasury Department," Ali Abedzadeh told the state-owned newspaper Iran in remarks published on Sunday, adding that there was no precise timeline for the written contract to be implemented before US Treasury permission.

He said the reported value of $17bn for the contract was not final and that more details would be provided after further negotiations.

"Out of 250 planes in the country, 230 need to be replaced," Abedzadeh added.

With the deal, Boeing becomes the first major American company to enter into a deal with Iran following the lifting of the nuclear sanctions earlier this year.

Boeing confirmed on Wednesday that it was in talks with Iranian airlines interested in buying its passenger planes.

"We have been engaged in discussions with Iranian airlines approved by the [US government] about potential purchases of Boeing commercial passenger airplanes and services," the company said in an email to the AFP news agency.

In February, the US company was granted approval from the US government to explore resuming sales to Iran after US sanctions were partially lifted in January.

Financial hurdles

So far, Boeing has only been granted permission to present its products to IranAir and a handful of other airlines as it tries to catch up with Europe's Airbus, which won a provisional deal earlier this year for 118 jets worth $27bn.

Iran has ordered about 200 planes in total from three Western manufacturers since mid-January when economic sanctions were lifted following a deal on Tehran's nuclear programme.

Richard Aboulafia, an aviation and aerospace analyst at the Teal Group, said in an interview that while there are a number of people talking up the deal, there's "very low level" of likelihood that most of the jets would be delivered to Iran.

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In an interview with Al Jazeera, Aboulafia said that Iran has "no money" to pay for the deal.

"It's great that they are going to do this deal, but it's more talk than actual money," he said.

"The biggest hurdle is financial. A lot of financiers are not comfortable with financing planes going to Iran".

He said that an economy that is under the control of a state like Iran "is not a recipe for success".

He also said that for Boeing, the deal is a way to show that there is "growth somewhere, anywhere", but added that Iran "is not a big market".

With reporting from Ted Regencia