Reza Jafarzadeh, a senior spokesman for the ICAO, has said that although no formal contracts have been signed all sides remain committed to the undertakings they have given, according to remarks reported by the official Islamic Republic News Agency. He added that the Ministry of Roads and Urban Development and the Foreign Ministry were together working on the issue.

Iranian airlines need to buy around 500 planes over the next ten years to replace their ageing fleets and to take advantage of the expected growth in air travel in the coming years. Iranian carriers currently own a 250-strong fleet, but at least 100 of their planes have either broken down or been stripped for spare parts.

In January, Airbus agreed to sell 118 aircraft to Iran in a deal worth up to $27bn. That was followed in June by Boeing tentatively agreeing to sell 80 planes to Iran Air, in a deal worth $17.6bn at list prices.

Farhad Parvaresh, managing director of Iran Air, told the local Fars news agency on July 17 that it hoped to finalise the deal with Airbus and another, smaller deal with France’s ATR by the end of August. The first planes could be delivered by the end of the year