Plane aerospace manufacturer Boeing has been granted a licence by the US Treasury to export certain commercial spare parts to Iran.
Aa Boeing spokesman said, the company had had no public dealings with Iran since 1979.
The company said in a statement that the licence had been granted to ensure flight safety.
The step is seen as part of a temporary agreement aimed at easing sanctions against Tehran that US secretary of state John Kerry reached with Iran last year.
Under the deal brokered in November, Iran agreed to suspend its nuclear activities for six months in exchange for sanctions relief from nations including the UK, China and the US.
Apart from Boeing, General Electric also said yesterday that it had received US permission to overhaul 18 engines sold to Iran in the late 1970s. The company added, the work would be carried out at GE facilities or at German firm MTU Aero Engines.
Passengers planes that Iran had bought before the 1979 hostage crisis, in which 52 US citizens were held hostage in Tehran for 444 days, are still being operated by Iran Air.
According to Iran, sanctions imposed after the hostage ordeal had prevented Tehran from upgrading its plane fleet, reducing aircraft safety.
A Boeing spokesman said, his company received the license this week and would now contact officials in Iran to determine which parts were needed.
According to GE spokesman Rick Kennedy, GE officials would meet with officials from Iran flag carrier Iranair and MTU in Istanbul next week to discuss Iran's needs.
According to Iran, the sanctions had prevented it from renewing its fleet. It had been forced to use Russian aircraft and to patch up jets that had long since exceeded their normal years of service. Since 1990 the country had more than 200 accidents, leading to over 2,000 deaths, official news agency IRNA said.
According to analysts, the sales could help US companies prepare for potential sales of new aircraft in the event of further easing of sanctions.