Saudi Arabia, the UAE and the US bought millions in weaponry made in Bulgaria, an investigation of the Balkan Investigative Reporting Network (BIRN) reveals.

Carried out by Bulgarian journalist Mariya Petkova and titled "War Gains: Bulgarian Arms Add Fuel to Middle East Conflicts", it tells the story of Saudi and UAE aircraft which over a certain periods of time landed at Sofia Airport and later took off with tons of cargo, in crates whose content was hard to discern.

Even though the governments of Saudi Arabia, the UAE and Bulgaria do not disclose the contents of the shipments, BIRN's investigation shows both countries "bought large quantities of weapons and ammunition from Bulgaria in the past two years".

It alleges it is almost certain that the weapons were "for use by local forces they support in the war in Syria, and possibly also the conflict in Yemen".

Armed forces of Saudi Arabia and the UAE both use modern Western weapons, whereas Bulgaria's output is more Soviet-style, the text adds.

A Bulgarian source is quoted as saying the weaponry was "intended for Syrian opposition fighters, with later shipments possibly also being used in Yemen". Other sources are cited later on who suggest countries such as Yemen, Iraq and Syria are where the Bulgarian weapons are used.

The US, however, also purchased arms from Bulgaria as part of its training and equipment program for part of the Syrian opposition.

Previously, under Communism, the Bulgarian Communist Party (BKP) used its strong trade links with the Middle East and Africa to export there the products of its huge arms intustry.

According to an arms trader quoted by BIRN, however, this production shrunk dramatically after the fall of communism, but this only lasted until 2006 when "sales began to pick up" and had nearly quadrupled eight years later. In his words, arms dealing in Bulgaria "is still more lucrative than drug smuggling"