Austrian Airlines will re-evaluate its Vienna-Tehran services later this month after being the latest airline to be caught up in an international diplomatic dispute.
Austrian has cut its Vienna-Tehran services from five a week to three and now picks up fuel in Azerbaijan on the return flight, after being told by the Iranian authorities that its aircraft would no longer be able to refuel at Tehran after 19 April.
According to Iran's civil aviation authority, a block on fuel supplies to several foreign carriers was introduced as a response to United Nations sanctions against Tehran.
The latter were introduced in response to Iran's nuclear ambitions, which the Middle East nation insists are purely for peaceful purposes but which western nations fear are aimed at developing nuclear weapons.
The US stepped up its own sanctions against Iran last June as part of the western campaign of pressure on the country. These resulted in decisions by several Western European fuel providers not to renew contracts with Iran Air and privately-owned Iranian carrier Mahan Air for fear of falling foul of the US measures.
In response, Iran's vice-president Mohammed Reza Rahimi was cited by the Iranian press last month as saying that Iran "decided immediately to strike back and banned supply of fuel to Western passenger planes landing in Iran".
According to Austrian Airlines: "We're continuing to operate a nonstop Vienna-Tehran flight but on the return we're making a stop in Baku to do some refuelling there." The fuel stop adds around 1h 45m to the return flight, he added.
Dutch flag carrier KLM said the airline had been operating a similar flight pattern since the end of last year, flying direct from Amsterdam to Tehran but making a fuel stop at Athens on the return leg - although this could be omitted if several factors including load factor and weather conditions permitted a nonstop leg.
British Midland International has introduced a fuel stop at Yerevan, Armenia, in both directions, "due to fuel supplies being restricted by the authorities in Iran", according to a written statement from the carrier. Alitalia's Tehran services now include a fuel stop in the Turkish capital, Ankara.