DUBAI — Tajikistan’s Transportation Ministry has grounded all flights by Tajik-registered cargo company Asia Airways after one of the company’s Antonov-12 jets crashed in South Sudan.

Antonov An-12

The first prototype flew in December 1957. Over 900 had been built, in both military and civilian versions, before production finally ended in 1973. The An-12BP entered Soviet military service in 1959. In terms of configuration, size and capability, the aircraft is similar to C-130 Hercules. Military Soviet and former-Soviet examples have a defensive tail gun turret.

The head of the Transportation Ministry civil aviation department, Yusuf Rahmonov, said in remarks reported by Asia-Plus that authorities in South Sudan are now investigating the causes of the accident, which killed around 40 people. The crew on the Antonov, which was built at a factory in Uzbekistan in 1971, reportedly included citizens of Russia and Armenia.

Russian tabloid website LifeNews, which is known to have strong connections to security agencies in Moscow, cited Russian aviation authorities as speculating that the plane may have crashed as it was overloaded. “Aircraft of this type are designed to carry around 21 tons of cargo, but commercial carriers in the Third World countries often increase that to 30-25 tons”, the website reported, citing unnamed officials.

Officials in Tajikistan are stressing that they deem the craft’s operator, which they say is Armenian company Ala International Limited, ultimately responsible for maintenance of the plane. But Armenian authorities have been quick to deny their liability and appear eager to pass the buck back to Tajikistan. A spokesman for the national aviation authorities in Yerevan, Ruben Grdzelian, has said that neither Ala International Limited nor the Antonov are registered in Armenia, RIA-Novosti news agency reported.

Asia-Plus has in turn suggested Ala International Limited is registered in the United Arab Emirates. Indeed, many air freight companies are for convenience registered in offshore locations like the Persian Gulf.

Asia Airways has not published any statements on the Antonov crash on its official website, but the company does state that between 2007 and 2014, the company underwent 12 international audits by U.S. and European clients working in Afghanistan and the United Arab Emirates. The cargo company said it was also subject to two audits by Tajikistan’s own aviation authorities.

The company’s customers have included the government of Tajikistan, for which it transported two 127 ton transformers intended for ongoing construction work at the Sangtuda-2 hydropower project from Tehran.