Azerbaijan's SilkWay Airlines has transported ammunition on at least 350 diplomatic flights, Bulgarian journalist Dilyana Gaytandzhieva wrote in an investigation for the most widely circulated Bulgarian newspaper, Trud, on July 2. Gaztandzhieva said that she had received a document cache about the flights from the Twitter account of the local chapter of Anonymous, the global hacker network.

The International Air Transport Association (IATA) bans the transport of dangerous products by civil aircraft, and the companies that wish to transport such goods must apply for exemption. Nevertheless, SilkWay Airlines has managed to obtain permission to transport ammunition as cargo on its civil planes to and from numerous countries, including Germany, the UK, Greece, Poland, Turkey, Saudi Arabia, Bulgaria, Serbia and Romania, among others.

The investigation reveals that American companies have been among SilkWay Airlines' main clients for the transport of ammunition, and that the airline has transported up to $1bn worth of explosives like PG-7V and PG-9V grenades. American arms trading company Purple Shovel, in particular, has used its services to deliver orders to the government of Azerbaijan and to the Incirlik military base in Turkey. The company appears to have sourced its grenades from Bulgaria, where one of its employees died in an accident related to the detonation of a rocket-propelled grenade in 2015.

SilkWay Airlines has also provided services to Chemring Military Products, another American arms company, Orbital ATK and Alliant Techsystems Operations. The latter reportedly transported almost $500mn worth of grenades from Serbia to Afghanistan using SilkWay Airlines.

Another important contractor for the airline has been the government of Saudi Arabia, which has reportedly hired it 23 times to carry weapons from Bulgaria, Serbia and Azerbaijan to the cities of Jeddah and Riyadh in the desert Kingdom.

The investigation makes uncorroborated allegations that the weapons transported to Saudi Arabia, but also to Burkina Faso and the Republic of Congo ended up in the hands of terrorist groups.

This is not the first time that the Azerbaijani airline, which is owned by the family of the country's president according to the Panama Papers document cache, has made the headlines. In 2016, one of its airplanes crashed in Afghanistan, killing the seven crew members on board.

The airline has recently been bolstering its fleet by purchasing Boeing aircraft.