US sanctions have forced Iranian airlines to put an end to direct flights between Kuala Lumpur and Tehran.
The world has become even more tighter to Iran's aviation industry, leaving Iranian citizens with lesser travel options. According to Iran government media outlets, the US sanctions prohibit US companies from supplying fuel to aircrafts with Iran registration. Those US fuel companies are the supplier to refueling companies in Malaysian airports. Malaysian refueling companies were informed by their US suppliers that they will be subject to punitive measures if they maintain refueling Iran's planes.
In 2008, the Iranian airline Mahan Air was subjected to sanctions by US, due to its links to the Quds Forces of Iran's Revolutionary Guard. Mahan Airlines and Iran Air are the only local airlines that have aircraft capable of flying the eight hours flight from Tehran to Kuala Lumpur.
Prior to the pandemic, the Tehran - Kuala Lumpur route operated three times a week before being suspended and returning as a once-weekly flight.
Flightradar24.com shows Mahan has a weekly service, flight W583, between Tehran Iman Khomeini International Airport (IKA) and Kuala Lumpur International Airport (KUL). Since June 25, the return trip, W582, has not been a nonstop direct flight as previously. After leaving KUL, the flight has been diverting to Thailand's Bangkok Suvarnabhumi Airport (BKK) or, more recently, to Hazrat Shahjalal International Airport (DAC) in Dhaka. Yesterday, flight W582, operated by an A340 registration EP-MMR, was scheduled as a direct flight from Kuala Lumpur to Tehran. However, the aircraft diverted to Dhaka and later departed for Tehran at 02:08, ultimately arriving in Tehran today at 05:32. It is possible that the Mahan Air flights are diverting for a refueling stop after being denied fuel at KUL, but this is not confirmed in the reports.