Iran is planning to buy 400 passenger planes in the event of Western sanctions being lifted, according to the country's top aviation official.

The move could provide a potential windfall for Western manufacturers including Airbus and Boeing.

Iran won partial relief from strict economic sanctions in January, having agreed to negotiate with Western powers over its disputed nuclear programme. Iran agreed to relax its nuclear activities for the duration of the negotiation process, which is almost four months into its six month time frame.

A comprehensive deal has so far remained elusive, although analysts believe that the parties are closer to a deal than they have been at any point in the last decade.

"Iranian airlines will be ready to buy 40 passenger planes every four years for 10 years if sanctions are lifted," Ali Reza Jahangirian, head of Iran's Civil Aviation Organisation, told the Ettelat newspaper on Thursday.

Decades of Western sanctions have left Iran's airplane fleet in bad shape. Out of 250 commercial planes, around a hundred are "not functional" and in dire need of repair, Jahangirian said.

"We have got very positive signals from Western companies, including Boeing and General Electric about getting new spare parts for our planes," he added.

Under the current deal, which offered Tehran partial relief on sanctions, companies are allowed to sell a limited amount of commercial plane parts and services to Iran. Moreover General Electric won approval from the United States Treasury to service 18 engines sold to Iran four decades ago.

Boeing and Airbus are the main contenders to capitalise should the Iranian market open up in the future, as Iran already has vintage aircraft from those manufacturers.

Iranian President Hassan Rouhani won election on a platform of improving Tehran's relations with the rest of the world and boosting its ailing economy. Despite facing pressure from conservative hardliners at home, Rouhani has urged foreign companies to invest in Iran when opportunities arise.