A criminal case has been filed against the illegal sale of four MiG-31 Foxhound aircraft hulls at $5 each instead of $3.7m by a Russian investigative agency in Nizhny Novgorod, Russia.

The sale was revealed in an anti-corruption check to see if regulations were followed during the sale of items from the Sokol aircraft construction plant located in the Russian Volga city of Nizhny Novgorod.

The agency said that unidentified officials from the local department of the Agency for State Reserves unlawfully included four MiG-31 hulls onto a list of sale items, RIA Novosti reports.

The act resulted in the purchase of the long-range supersonic interceptor aircraft that were not for sale by a dummy firm that was not entitled to trade in arms and military hardware,.

Although the hulls were sold without engines and weapons, the estimated worth of each airframe is about $3.7m.